Background: Phenol is an estrogenic and toxic compound and people are widely exposed to it, in different ways.  OBJECTIVES: The aim of this study was to determine  the  negative effects of phenol on the fertility of male mice, by investigating sperm parameters including viability, motility, fertility rates and daily sperm production (DSP). METHODS: A total of 106 adult NIH mice were divided into four groups, one control and three experimental groups (n=13). The treatment groups were given daily dose of phenol for 35 days through gavage method (30, 75 and 100 mg/kg) while the control group received only normal saline. At day 36, six mice were sacrificed from each group. Gonadosomatic index (GSI), viability, motility and daily sperm production were determined carefully. The remaining 7 mice from each group were used to mate with 2 female mice. On GD10, the female mice were sacrificed and the fertility was verified. RESULTS: Daily sperm production in treatment groups decreased significantly compared to the control group (p≤0.05). Body weight, sperm motility, viability and fertility percentage were significantly decreased in 75 and 100 mg/kg groups in comparison with the control group (p≤0.05). While the testes showed no significant changes in weight in any groups. Gonadosomatic index in the treatment groups compared to the control group, was significantly decreased (p≤0.05). CONCLUSIONS: Pure phenol could reduce fertility rate through decreasing motility, daily sperm production and sperm viability.