In 386 patients with acute inferior myocardial infarction (AIMI) who were admitted to our institution from 1984 to 1990, temporary pacemaker (TP) was required in 34 patients (9%) due to disturbances in the genesis and/or conduction of the electric stimulus (Group I). The remainder, 352 AIMI, conform the Group II. Each group was divided into groups depending on the presence (Groups Ia and IIa) or absence (Groups Ib and IIb) of right ventricular necrosis (ECG criteria: ST elevation greater than 0.1 mV in a V3r and V4R). Clinical data (cardiovascular risk factors, history of myocardial infarction or angina, CPK and CK-MB peak, Killip class, atrioventricular block and right ventricular infarction) and hospital mortality rate and its cause were analyzed. The Group I patients related to Group II had significantly higher diabetes rate (p less than 0.01), CPK and CK-MB peak (p less than 0.001), Killip class (p less than 0.001), right ventricular involvement and atrioventricular block (p less than 0.001), the mortality rate equally was statistically higher (Group I, 11 patients, 31%, versus group II, 38 patients, 11%) (p less than 0.001). The Group Ia patients related to Group Ib had a higher CPK and CK-MB peak (p less than 0.001), Killip class and atrioventricular block (p less than 0.001). The mortality rate was statistically equal. The group IIb patients related to Group IIb patients had a higher CPK and CK-MB peak (p less than 0.001), without differences in the mortality rates.(ABSTRACT TRUNCATED AT 250 WORDS)