An outbreak of salmonellosis, involving cases of infection with Salmonella enteritidis phage types (PT) 5c and 6a, occurred across Scotland between May and August 2000. In total, 70 outbreak cases were microbiologically confirmed. Preliminary investigation suggested that consumption of food, especially chicken dishes, from Chinese restaurants or take-aways (food businesses) was a risk factor for infection. A matched case-control study demonstrated a statistically significant association (OR 22·4, P=0·0024) between infection and consumption of food from Chinese food businesses. A cohort study of novel design suggested that chicken was an important vehicle of infection. However the result did not reach statistical significance (OR 1·7, P=0·3). Extensive environmental investigation was unable to identify the source of the suspected contaminated chicken.