In 292 patients with suspected acute myocardial infarction given thrombolytic agents, we describe the delay time between the onset of pain and the start of thrombolysis and relate the observations to the prognosis. In 3%, treatment was started 1 h or less and in 22% 2 h or less after onset of symptoms. The median delay time between onset of symptoms and arrival in hospital was 1 h 38 min, and the median delay time between the arrival in hospital and start of thrombolysis was 1 h 25 min. A very strong association between delay time to thrombolysis and mortality during 2 weeks and 1 year of follow-up was observed.