The aim of the PIMICS project was to create, for the first time in Switzerland, a registry of data concerning epidemiology and therapy in patients hospitalised for acute myocardial infarction covering all regions of the country. During 1995/96 73 Swiss hospitals of all categories took part in the PIMICS project. The ratio between males and females in the 3877 registered patients was 2.6:1 (2791 men vs. 1086 women). Female patients were significantly older than males (70.4 +/- 12.0 years vs. 63.4 +/- 12.6 years; p < 0.0001). The prevalence of risk factors differed between men and women: significantly more women had hypertension or diabetes, whereas smoking was more prevalent in males. The median delay between onset of symptoms and arrival at the hospital was 5.5 hours. Thrombolysis and primary angioplasty were more frequently performed in men (40.4% vs. 31.2% in women, p < 0.0001, and 5.7% in men vs. 3.5% in women, p = 0.005 respectively). During the acute phase males were treated more frequently with betablockers. The overall in-hospital mortality was 9.1%. It was significantly higher in female patients (13.5% vs. 7.4% in men; p < 0.0001) and in patients with reinfarction (14.5% vs. 7.1%; p < 0.0001). The mean hospital stay was 12.6 +/- 5.3 days. Only 7.7% of all patients with acute myocardial infarction were discharged within 6 days. At discharge, 51.7% were treated with betablockers and 69.3% with aspirin; 44.8% received ACE-inhibitors and only 13.8% lipid-lowering drugs. Follow-up measures such as coronary angiography and/or angioplasty or bypass surgery were performed significantly more often in males (45.0% vs. 32.9%; p < 0.0001). Likewise, men were more frequently assigned to a rehabilitation program than women (38.2% vs. 32.9%; p = 0.0004). The pre-hospital delay in patients with acute myocardial infarction remains too long. Primary and secondary prevention should be intensified in high risk groups, particularly in females. Thrombolysis and primary angioplasty as mainstays of treatment in acute myocardial infarction are generally used too sparingly, especially in women. With such measures the hospital stay could be shortened further.