The incidence and hospital course of acute myocardial infarction were observed among randomly selected 560 patients. The mean age of the patients was 53:t6.67 years with male-female ratio 2.6:1. The incidence of right bundle. branch block (RBBB) was 15% (84 out of 560 patients). New RBBB, old RBBB and RBBB ofindeterminate age were observed in 33(39.25%),23 (27.40%) and 28(33.25 %) cases respectively. RBBB was isolated in 50 (60%) cases and bi fascicular in remaining 34(40%) cases. The rate of use of thrombolytic was greater in RBBB group than non-RBBB group (52% vs 30.67%, P<0.05).