The incidence of hypotension in patients treated with thrombolytic agents for myocardial infarction was investigated in a series of 71 patients, 17 treated with urokinase, 35 with rtPA and 19 with APSAC. Hypotension was observed in 23.5% of the first group, in 5.5% of the second, and in 42.10% of the third (p < 0.002 between rtPA and APSAC). In the inferior location hypotensive reaction was much more frequent than in anterior one (p < 007) especially if a right ventricular involvement was associated. Even if hypotension is a minor and generally harmless complication, it poses many practical problems, and its occurrence must be taken into account when choosing a fibrinolytic treatment.