Abstract: Rats with Pneumocystis carinii pneumonia （PCP） were established by hypodermic injection of dexame-thasone and treated by brucea javanica combined with fructus psoraleae 2 ml （Brucea javanica 0.12 mg and fructus psoraleae 1.0 mg） per rat per day for 7 days or 14 days. The effect of cyst-killing and the pathological change were observed under transmission electron microscope. Lung damage was alleviated or repaired， and a significant reduction of cysts was shown in the treatment group. The results show that a combination of Brucea javanica and fructus psoraleae played a significant restraining and killing effect on cysts, and helped repair the impairment of pneumonia.

Key words: Pneumocystis carinii pneumonia, Rats, Brucea javanica, Fructus psoraleae, Therapeutic effect, Transmission electron microscope