Aim: To study the preventive effect of recombinant human basic fibroblast growth factor ( rh-bFGF) on restenosis after percutaneous transluminal coronary angioplasty (PTCA). Methods: Sixty male Wistar rats were randomly divided into sham operation group, intima. injured group, and intima injured plus rh-bFGF treated group. Rat carotid arteries were injured using a balloon catheter except sham operation group. The rats of rh-bFGF treated group were injected im rh-bFGF 10 kU.g(-1).d(-1) after intima was injured. Ten rats in each group were killed on d 7 and d 14 after injury, respectively. [H-3] Thymidine incorporation assay and pathological examination were carried out to each vessel. Results: (1) Seven days after injury, the average intimal. thickness in sham operation group, intima. injured group, and rh-bFGF treated group was (7 1), (32 +/- 11), and (17 +/-3) mum; average intimal area was (384 +/- 145), ( 1530 +/- 817), and (586 +/- 185) mum(2); the numbers of smooth muscle cells in neointima per transect were 0 +/-0, 146 +/- 18, and 105 +/- 26; the ratio of the collagen area to intimal area plus medial area were 0.29 +/-0.09, 0.7 +/-0.3, and 0.30 +/-0.14; [H-3] thymidine incorporation were (17 +/-6), (62 +/- 23), (20 +/-8) kBq/g tissue, respectively. (2) Fourteen days after injury, the average intimal thickness of sham operation group, intima injured group, and rh-bFGF treated group was (8 +/-1), (41 +/-9), and (20 +/-3) tan; average intimal area was (391 +/- 134), (1761 +/- 337), and (731 +/- 124) mum(2); the numbers of smooth muscle cells in neointima per transect were 0 +/-0, 145 +/-9, and 102 +/-6; the ratio of collagen area to intimal area plus medial area were 0.28 +/-0.14, 0.59 +/-0.21, and 0.38 +/-0.03; [H-3] thymidine incorporation was (15 +/-4), (57 +/- 11), and (22 +/-6) kBq/g tissue, respectively. Conclusion: Large dosage of rh-bFGF inhibits neointimal hyperplasia and reduces restenosis after balloon injury.