The efficacy and safety in using a new low-profile perfusion balloon catheter (PBC) as the initial balloon in percutaneous coronary angioplasty (PTCA) was assessed retrospectively in 61 patients: 43 males, mean age 62 +/- 12 years. Thirty-three patients (54%) had unstable angina. PTCA was performed using an improved PBC in the following vessels: LAD 40%; CX 21%; RCA 24%. Lesion morphology was: Type A 21%; Type B1 18%; Type B2 40%; Type C 21%. Mean artery size was 3.01 +/- 0.53 mm. Mean PBC size was 3.14 +/- 0.45 mm. The mean number of inflations used was 2.85 +/- 2.0. The mean longest inflation was 415 +/- 213 sec and the total inflation time was 663 +/- 342 sec to a mean maximum pressure atmosphere of 7.85 +/- 2.0 bars. The number of balloons used per procedure was 1.2 +/- 0.44. In 50 patients (82%) only one balloon was used during the PTCA. PTCA was successful (< 50% diameter stenosis without major complications) in 60 patients (98.4%). Mean diameter stenosis at baseline was 82 +/- 9.5% and post-angioplasty 13 +/- 10.6%. A mild intimal tear occurred in 6 patients (9.8%). A stent was implanted in 3 patients (4.9%) due to severe dissection. In hospital reocclusion occurred in one patient (1.6%). There were no deaths or emergency bypass surgery. A low profile PBC is safe and effective as an initial balloon in PTCA. It may reduce the number of balloons used and inflations per procedure.