Objective:To observe the effect of percutaneous tr ansluminal coronary angioplasty (PTCA) on coronary circulating tumor necrosis fa ctor-α (TNF-α) activity. Methods: Plasma TNF-α levls were measured with radioimmunoassay and bioactive assay respectively. Result s: Plasma TNF-α activity in femoral artery (AO) was significantly incr eased immediately after PTCA ［(15.86±3.75) U/ml vs （41.32±4.36） U/ml， P<0.01］, and plasma TNF-α activity in coronary sinus was remarkably incre ased immediately after PTCA　［(16.72±4.14） U/ml vs （65.61±6.25） U/ml, P<0.01］. There was no change in plasma TNF-α activity in AO 24 h after PT CA ［(18.32±5.12） U/ml vs （15.86±3.75） U/ml, P>0.05］. Conclu sion: The increase in plasma TNF-α activity after PTCA may be associat ed with the injury of coronary artery caused by PTCA, suggesting that TNF-α ma y be involved in the coronary occlusion and the development of coronary restenos is after PTCA.