A case-control study was based on "unselected" transient ischemic attacks (TIAs) in a middle-aged Italian population. The identified cases included 52 prevalent and 25 incident TIAs. There was an incidence rate ratio (female/male) of 1.8 for definite cases. Comparison with the whole population for medical history of hypertension, diabetes and heart attack showed age/sex-adjusted odds ratios of 4.3, 2.1, 7.9 for incident cases. The results were similar when a more detailed investigation of risk factors was performed with all the cases and a random sample of the controls. Moreover, female sex had an odds ratio for incident cases of 3.3 (95% confidence interval 1.0-11.3) after adjustment for age and presence of all the main risk factors. The presence of at least one cardiopathy showed an odds ratio of 8.3 for incident cases (95% confidence interval 2.4-28.4).