This open, non-comparative, PMS study of fosinopril (Staril) involved 12,067 hypertensive patients assessed at baseline and after two and six months of treatment; 10,791 patients provided evaluable data with 5.2 months average treatment totalling 4667 patient-years. Adverse events were reported in 24% of patients, the most common being mild-to-moderate cough (6.05%). Events considered possibly related to fosinopril were reported in 15% of patients, the frequency being lower in younger patients, males and those receiving fosinopril monotherapy. Patient well-being improved during the study. At the end of the study, most patients were taking fosinopril 10 mg once daily. Mean reductions in systolic and diastolic blood pressures were -11.0% and -11.7%, respectively; 71.3% of patients were 'responders'. No important differences were observed between subgroups. This study found fosinopril to be effective, well tolerated in a broad range of hypertensive patients, and with no previously unrecognised adverse events reported.