Venous thromboembolism (VTE), comprising deep venous thrombosis (DVT) and pulmonary embolism (PE), is a common and preventable cause of morbidity among individuals and hospital in-patient mortality. Further, it imposes a substantial burden upon the community and its health care system and economy. Studies performed in Western societies suggest that the annual incidence of DVT is about 0.8 to 1.2 per 1,000, PE about 0.3 to 0.6 per 1,000, and VTE about 1.0 to 1.8 per 1,000. However, it is not known if these estimates can be generalised to the Australian population because of differences in ethnic composition and other risk factors for VTE among the different populations. In this thesis, I undertook a prospective, community-based cohort study over a 13-month period in 2003 – 2004 to determine the incidence and crude event rate of symptomatic, objectively verified VTE in north-east metropolitan Perth. The study population was broadly representative of the national Australian population in terms of age, sex and ethnic distribution. Cases were identified through multiple overlapping sources. The incidence of DVT, PE and VTE in the community were 0.52 (95% confidence interval, CI: 0.41 – 0.63), 0.31 (95% CI: 0.22 – 0.40) and 0.83 (95% CI: 0.69 – 0.97) per 1000 per year, respectively. The annual incidence of DVT, adjusted to the World Standard population, was 0.35 (95% CI: 0.26 – 0.44) per 1000, PE 0.21 (95% CI: 0.14 – 0.28) per 1000 and VTE 0.57 (95% CI: 0.47 – 0.67) per 1000. The crude event rate for VTE was 0.85 (95% CI: 0.71 – 0.99) per 1000 per year. These findings suggest that the incidence of DVT, PE and VTE are lower than in other Western societies studied. Possible reasons include a lower prevalence of exposure to causal risk factors (genetic and environmental) and incomplete case ascertainment. Knowledge of the local incidence and event rate allows health planners to allocate appropriate resources and evaluate cost-effective preventive measures.