Background Cnidium monnieri (L.) Cuss. has been used for a long time according to the traditional experiences and documentation in order to treat male sexual disorders. Osthole is one of the main bioactive components in Cnidium monnieri (L.) Cuss. In this study, we aimed to evaluate the effect of Cnidium monnieri (L.) Cuss. fruit extract of which osthole content was 35% (determined by HPLC method) on sexual behaviors in adult male rats. Methods Cnidium monnieri (L.) Cuss. fruit extract was administered orally at the dose of 150 mg/kg b.w and after 30 min, male rats were coupled with receptive adult female rats to evaluate sexual behaviors, including mounting and intromission. Results Cnidium monnieri (L.) Cuss. fruit extract at the dose of 150 mg/kg b.w increased the percentage of rats that mounted and intromitted; increased the intromission frequency and decreased mounting latency and intromission latency. Conclusion Cnidium monnieri (L.) Cuss. fruit extract increased the ability to mount and intromit in rats, and scientifically support the traditional use of Cnidium monnieri (L.) Cuss. in treatment of male sexual disorders.