AIM: To explore the activative effect of water extract from cultured mycelium of Paecilomyces cicadae (P. cicadae) on peritoneal macrophages (PM?) and alveolar macrophages (AM?) of rats.METHODS: The rats were randomly divided into four groups: normal control group(Ⅰ), cyclophosphamide (Cy) group (Ⅱ), P. cicadae group(Ⅲ), Cy+ P.cicadae group(Ⅳ).The rats were bred in the same circumstance and were administered with corresponding drugs by subcutaneous injection for 26 days. PM? and AM? of rats were irrigated by normal saline and collected by centrifuge and incubated in a humidified incubator for 2 h at 37 ℃. The activities of acid phosphatase (ACP) and lactate dehydrogenase (LDH) in the PM? and AM? were determined by biochemical methods, and the capability of PM? and AM? in phagocytosis of neutral red were measured by colorimetric method too. RESULTS: After administering P. cicadae to rats, the activities of ACP and LDH in PM? and AM? of normal rats were elevated significantly,and the reduction of the activities of ACP and LDH in PM? and AM? of rats due to Cy was notably antagonized, and the capability of PM? and AM? phagocytizing the neutral red were strengthened significantly.CONCLUSION: P. cicadae can activate the PM? and AM? of rats.