Background and purpose: Cyclophosphamide (CP) is a chemotherapy drug extensively used as an antineoplastic agent in treatment of various cancers. However, it is known to cause several adverse effects including reproductive toxicity. Achillea millefolium (AM) is a medicinal plant with potential antioxidant properties. The aim of this investigation was to evaluate the effects of different doses of AM extract on body weight, sperm parameters, and apoptotic changes in CP treated mice.

Materials and methods: Sixty four male NMRI mice were arranged into 8 groups. Group1 received normal saline, and groups 2, 3 and 4 received AM extract in low, medium and high doses, respectively. Group 5 received CP and groups 6, 7 and 8 had low, medium and high doses of Achillea millefolium extract, respectively plus CP. Treatments were continued for 35 days. Afterwards, the animals’ weight, sperm quality and apoptosis rate were evaluated.

Results: CP decreased body weight and testicular weight, imposed negative effects on sperm parameters and increased sperm apoptosis compared to the control group. The high-dose of AM produced deleterious effects. Medium doses of the extract did not show any significant effect, but low dose of the extract was able to compensate the toxic effects of CP.

Conclusion: In this study, AM had dose-dependent manner. In other words, at low dose it prevented CP toxicity, in medium dose it had no effect, but in high dose it improved CP toxicity.