Percutaneous transluminal coronary angioplasty was employed in a group of 178 patients (151 males and 27 females) aged 24 to 68 years (mean 42 +/- 12 years). Stable angina was diagnosed in 136 patients, unstable angina in 38, and an acute infarct in 4. In 150 patients there was one, in 25 two and in 5 patients 3 target stenoses. Lesions were localised in the left anterior descending artery in 130 cases, in the circumflex artery in 32 cases and in the right coronary artery in 49 cases. The attempts to dilate 78 stenoses with a fixed-wire, non-guided system was successful in 78% of cases. Success rate with the over-the-wire system was 85%. In total, we successfully dilated 173 patients, i.e. 82%. The highest success rate, 85%, was achieved in lesions localized in the left anterior descending artery and lowest in lesions localized in the left circumflex artery. Success rate in the groups with stable and unstable coronary artery disease was similar. Complications occurred in 6% of the cases. Experience of the operators involved in PTCA is an important factor influencing the success rate. In the first year of using this technique, good results were achieved in 48% of patients, in the second year in 63%. During the next two years 86% of the stenoses were successfully dilated.