Transluminal balloon angioplasty of Blalock-Taussig's stenotic anastomosis was performed in 37 patients with various congenital heart diseases in 1989 to April 1993. The patients' age ranged from 3 to 16 years (mean 8.4 +/- 0.5 years). Arterial blood oxygen saturation varied from 38 to 74% (mean 62.4 +/- 1.5%). Hemoglobin amounted to 14 to 28.4 g% (mean 19.0 +/- 8.4 g%). Phonocardiography recorded no or low-amplitude systolic-diastolic anastomosis murmur in points IV-V in all patients. After balloon anastomosis dilatation, arterial blood oxygen saturation increased, on an average, from 62.4 +/- 1.5% to 81.2 +/- 1.2%. Anastomosis angiometry performed prior to and following balloon dilatation showed its significant dilatation (on an average, from 3.39 +/- 0.19 to 5.26 +/- 0.24 mm). There was a distinct systolic-diastolic murmur of anastomosis on the PhCG. Post-balloon-dilatation complications occurred only in 3 cases: femoral thrombosis in 2 patients and pulmonary edema in 1. The late results were studied in 18 patients at months 2 to 40. None of them showed deterioration of clinical results after balloon dilatation. Eight patients were radically operated on. The best results were achieved in patients with discrete anastomosis stenoses and when balloons whose diameter corresponded to that of the subclavian artery and equal to 0.92-1.2 mm were used. A good effect following balloon angioplasty was observed in 24 (64.9%), satisfactory and poor results were found in 12 (32.4%) and 1 (2.7%), respectively.(ABSTRACT TRUNCATED AT 250 WORDS)