Objective To assess the therapeutic effect of garlicin on Pneumocystis carinii pneumonia (PCP) of immuosuppressed rats. Methods The Wistar rats were injected intramuscularly continually with dexamethasone for eight weeks to establish the rat model of PCP. The rats were treated with garlicin, meanwhile control groups without treatment and with SMZ-TMP treatment were established respectively in PCP model. The efficacy was evaluated based on the lung weight, lung /body weight ratio and mean cyst number per 100 fields in lung print smear. Results The mean lung weight of the rats in garlicin is 1.73?0.17, lung/body weight ratio is 0.84?0.12, they are obvious lower than 2.31?0.35 and 1.25?0.35 of control (P