The administration of Mesquite pod extract (containing mesquitol, daidzein and genistein) to female and male rats disrupts reproductive variables. However, its effect on fertility is not known. This study evaluated fertility in male and female rats treated with mesquite pod extract, comparing its effects with those of daidzein and estradiol. The following treatments were given for 30 days to groups of female and male rats: vehicle, mesquite pod extract, DAI and E 2 . Treatments were administered subcutaneously for 30 days. These extract disrupted both the female and male sexual behavior in a similar way to DAI, but less than E 2 . Mesquite pod extract increased the number of days in estrus and decreased lordosis intensity during proestrus. Mesquite pod extract-treated males showed lower testicular and glandular weights, as well as decreased sperm motility, viability and count. In females treated with mesquite pod extract, the number of pups was lower than in control females, and 10 to 20% of pups were dead. These effects were similar to those with DAI-treatment. Despite the lower sperm quality, the fertility of mesquite pod extract-and DAI-treated males seem not to be disrupted, as they could impregnate control females. These results show that mesquite pod extract can disrupt female but not male fertility.