In order to assess the results of percutaneous transluminal coronary angioplasty of the proximal (before the first septal branch) left anterior descending artery lesions, we analyzed the results in 206 consecutive patients, aged 56 +/- 12 years. The distance of the lesion from the origin of the left anterior descending artery was measured in the right oblique angiogram. The location of the lesions proved to be very proximal (less than 0.5 cm from the origin) in 22 patients, intermediate (0.5-1 cm from the origin) in 26 patients and distal (greater than 1 cm from the origin) in 158 patients. The initial angiographic success rate was similar among the 3 groups of patients: 95.8% in those with very proximal and intermediate lesions and 98.1% in those with distal lesions. Occlusive dissection of the left anterior descending artery without involvement of the mainstem occurred in 3.8% of the patients with intermediate lesions and in 1.9% of those with distal lesions. No complications occurred in any patient with very proximal lesions. The clinical follow-up was 25.2 +/- 12 months; angina recurred in 15.5% (31 out of 206 patients). Coronary angiography was performed in 103 patients. Restenosis occurred in 42.3% of the patients with very proximal and intermediate lesions (11 out of 26) and 31.2% of those with distal lesions (24 out of 77). In conclusion, in most patients with very proximal and intermediate lesions of left anterior descending artery, coronary angioplasty can be performed with low risk. The location of the lesion in the proximal portion of left anterior descending artery does not affect the overall success rate.(ABSTRACT TRUNCATED AT 250 WORDS)