Summary: The effects of Shenmai injection (SMI) and aminophylline on apoptosis of small airwaysmooth muscle cells (SASMC) and the Fas/FasL expression in rats with papain-induced emphyse-ma were investigated. Rat emphysema model was established by a single intratracheal instillationof papain. Apoptosis and Fas/FasL expression of SASMC were detected by immunohistochemistrySABC and TUNEL assay at day 1, 3, 5, 7, 15, 30 after modeling, and the effect of SMI andaminophylline on them were observed. The results indicated that the Fas/FasL expression positiverate in SASMC was 2.31±0. 55/1. 28±0. 47 respectively. After a single intratracheal instillationof papain, the expression of Fas/FasL positive rate in the placebo group was increased in a time-dependent manner. SMI could inhibit the expression of Fas/FasL, but aminophylline couldnt.The positive rate of apoptosis in the control group was 0. 87±0. 32. After a single intratracheal in-stillation of papain, the SASMC apoptosis positive rate in the placebo group was increased in atime-dependent manner. The SASMC apoptosis rate in all groups was declined after treatmentwith SMI, but the effect of aminophylline was not obvious. It was demonstrated that in the patho-genesis of emphysema Fas/FasL played an important role in the regulation of SASMC apoptosis.SMI influenced the expression of Fas/FasL and declined SASMC apoptosis by inhibiting the releas-ing of inflammatory media and played an important role in the therapy of emphysema.