To determine antiographic factors involved in left ventricular aneurysm formation after myocardial infarction, 50 patients with a first anterior wall myocardial infarction who underwent cardiac catheterisation within 6 months of infarction were evaluated. Extent of coronary artery disease and status of collateral circulation were studied in detail. Thirty patients had aneurysm in apical region while 20 patients showed aneurysm in anteroapical region. Coronary angiography revealed single-vessel disease in 17 patients, double-vessel disease in 17 patients and triple-vessel disease in 15 patients while in one patient coronary angiogram was normal. Fortynine patients showed significant involvement of left anterior descending artery which was poorly collateralised. Left anterior descending artery disease in association with inherent poor collateral blood supply may predispose for aneurysm formation after anterior wall myocardial infarction.