The aim of this investigation was to evaluate the hygiene of domestic food preparation practices. The traditional survey approach used to study this behaviour has problems of interpretation and verification. In this study direct observation, supplemented with food temperature measurements was used to gather information for the purpose of developing an understanding of the causes of domestic food poisoning. The food handling practices of 108 people preparing foods commonly implicated in outbreaks of food poisoning were analysed. A HACCP approach was employed and a standard measure of hygienic food handling behaviour, the Food Safety Risk Score, (FSR) was devised. The FSR score indicated the extent of the use of appropriate control measures during food preparation. The higher the score the greater the risk of unsafe food being produced. Scores expressed as a percentage, ranged from 0 to 65% with over half of the subjects scoring below 20%. More than half (60%) of the people cooked in advance of consumption but most (85%) cooked the food thoroughly. Few used any method to speed the cooling of cooked food. Temperature abuse during food transport and storage was exhibited by more than 40% of people. Cooked food was held at ambient temperature for prolonged periods by 19% of the people and was re-heated inadequately by 11%. The standard of personal hygiene of some participants was low. An assessment of the cleanliness of the domestic kitchen and the condition of equipment and surfaces used in food preparation, based on ATP measurements and a kitchen checklist showed that there was a wide variation in the standards found in homes. The great potential for indirect and direct cross contamination in the domestic kitchen was highlighted. The problems involved in persuading people to practise well-known food hygiene principles are considered and recommendations for improving domestic food hygiene are made.