Polycystic ovarian syndrome (PCOS) is a low grade inflammatory disease characterized by hyperandrogenemia and chronic anovulation. C-reactive protein (CRP), released by adipocytes, plays a key role in PCOS. Apis mellifera honeybee venom (HBV) contains a variety of biologically active components with various pharmaceutical properties. This study was designed to assess the possibility of HBV application as an anti-inflammatory therapeutic agent. To induce PCOS, 1 mg/100 g body weight estradiol valerate (EV) was subcutaneously (SC) injected into eight-week-old rats. After 60 days, 0.5 mg/kg HBV was administered SC for 14 consecutive days, and the results of PCOS treatment were investigated. Rats were then anesthetized with chloroform, and their ovaries and livers were surgically removed to determine histomorphometrical changes. Testosterone and 17-β-estradiol were detected by chemiluminescence immunoassay. In order to detect serum CRP, ELISA kit was used in three groups of EV-induced PCOS, HBV-treated PCOS and control animals. Thickness of the theca layer, number of cysts and the level of serum CRP significantly decreased in HBV group in comparison with PCOS group. Moreover, corpus luteum, as a sign of ovulation, was observed in HBV-treated ovaries which were absent in PCOS group. Our results suggest that the beneficial effect of HBV may be mediated through its inhibitory effect on serum CRP levels.(AU)