Background: International research has shown that socioeconomically disadvantaged groups experience significantly higher mortality and morbidity rates than other groups. Both cardiovascular disease (CVD) and diabetes are major contributors to Australia's burden of disease, and individuals from lower socioeconomic groups are more likely to be affected by both, and to have worse prognoses and outcomes. There is substantial research evidence that a range of preventive activities can reduce the morbidity and mortality associated with these conditions. Research in countries with good access to primary health care services has demonstrated that socioeconomically disadvantaged groups tend to have higher levels of medical consultations, but make less use of preventive care and screening services. This fact contributes to their poorer health outcomes, as diagnosis will typically occur later than for more advantaged individuals, thus leading to a poorer prognosis. However, to date, there has been little research on the differential utilisation of preventive health services for CVD and diabetes by different socioeconomic groups in Australia. To understand socioeconomic influences on the use of preventive health services, a comprehensive review of the literature of determinants of health service utilisation was conducted and a number of explanations for this relationship considered. It was proposed that the following factors are likely to be important in this relationship: differences in the perception of the availability of, and accessibility to health care, attitudes and beliefs toward preventive health care, having a regular source of care, perception of interpersonal care from general practitioners, and social support. A number of theoretical models were also reviewed; in particular, the Andersen Behavioural Model of Health Service Research Utilisation. Aims: This doctoral research program has described the relationship between socioeconomic position (SEP) and utilisation of preventive health services in relation to CVD and diabetes. It aims to improve the understanding of the determinants of uptake and utilisation of preventive health services in general practice by different socioeconomic groups in Australia. Methods: The study was conducted in Brisbane Australia, in 2004, using a cross-sectional design and a self-administered mailed survey for data collection. A sample of adults aged 25-64 years was selected randomly from the Brisbane Electoral Roll. A conceptual model incorporating a range of relevant socio-demographic, risk-factor and behavioural variables in the relationship between SEP and GP-based use of preventive health services was used to develop a self-administered questionnaire. The questionnaire was pilot-tested and then reviewed by a panel of international experts. A new self-administered questionnaire, the Health Service Utilisation Questionnaire (HSUQ), was developed. It included 79 items: 12 socio-demographic items; 10 items assessing health status, disease conditions and smoking status; 20 items assessing use of health services; and 37 items assessing the factors that might affect use of health services utilisation. The HSUQ was then mailed to 800 randomly selected survey participants. The survey response rate was 65.6 per cent. After exclusion of those patients with cardiovascular diseases and diabetes, the final sample size was 381, consisting of 155 males and 226 females. Socioeconomic indicators were individual education level and family income. Blood pressure, blood cholesterol and blood glucose check-ups by general practitioners (GPs) were used as the major outcome variables. Nine scales and two dichotomous variables that measure those potential factors were derived following Principal Component Analysis and reliability testing. The data were analysed separately by gender, and adjusted for age and each of the socioeconomic indicators. Statistical description, bivariate analysis and multivariable modelling in SPSS were applied for the data analysis. Results: The survey results were suggestive of socioeconomically disadvantaged people being less likely than more advantaged people to utilise preventive health services for CVD and diabetes. For males, the low socioeconomic groups recorded the least use of preventive health services among the three education and income groups, including blood cholesterol and blood glucose check-ups, while the high socioeconomic group recorded the greatest use of preventive health services. There was no apparent relationship between education level and blood pressure check-up, while individuals from low-income families were less likely to go for a blood pressure check-up. For females, most of the results suggested that the low socioeconomic groups were less likely than the high socioeconomic groups to have blood cholesterol and blood glucose check-ups. However, this was not the case for blood pressure check-ups. The results showed that the low and middle socioeconomic groups were more likely than the high socioeconomic groups to have BP check-ups. However, the low socioeconomic groups were still less likely than the middle socioeconomic groups to have a blood pressure check-up. Overall, there was a similar pattern between education and income and the use of GP-based preventive health services among both males and females. The findings from the examination of the mediating factors between SEP and the GP-based use of preventive health services suggested that socioeconomically disadvantaged adults (both low level of education and low income) are more concerned about transport and travel time to health care, and accessibility to health care in terms of finding a GP who bulk bills, the cost of seeing a GP and having a choice of GP. They are also less likely to have a regular place of care and social support. These potential factors are likely to result in a lesser use of preventive health services than their high-SEP counterparts. In addition, the findings also suggested that respondents with a low level of education have less-positive attitudes towards health care, and that those from low-income families do not have a regular care provider and are less likely to visit their GP for a preventive check-up in relation to CVD and diabetes in Australia. Conclusions: Strategies for reducing socioeconomic health inequalities are partly associated with changing social and economic policies, empowering individuals, strengthening social and family networks, and improving the equity of the health care system. Strategies have been recommended for implementation in general practice that are directed at targeting the needs of disadvantaged groups; for example, providing longer consultation time and actively offering information on preventive care. Implementation of health promotion programs is needed in disadvantaged areas to keep the community informed about the availability of health services and to make health services more accessible. The health care system needs to be geographically accessible through improvements to the transport system. In addition, improving access to a regular source of primary health care is likely to be an important step in encouraging low-SEP individuals to use preventive health services.