Ethnopharmacological relevanceNeem (Azadirachta indica A. Juss.) is native to India and belongs to the Meliaceae family. It has been used for centuries in Eastern medicine, and more recently, as a natural pesticide. Although the use of bioinsecticides is supported by organic food production, further research is needed on each formulation, particularly on their effects on organisms. Aim of the studyThis study evaluated the reproductive toxicity of an aqueous extract of neem leaves in male Wistar rats of reproductive age after eight days of exposure. Materials and methodsFor this study, 20 rats were divided into four groups of five animals each and treated with different concentrations: Group 1 received 10,000 ppm, Group 2 received 7500 ppm, Group 3 received 5000 ppm, and Group 4 served as the control, received distilled water. The animals were observed for eight days for any clinical signs of toxicity. Semen quality, including sperm motility and viability, was analyzed. ResultsNo significant differences in physiological changes were observed between treatments. However, sperm motility and viability were affected in a concentration-dependent manner, with the group that received the highest dose exhibiting inviable spermatozoa. ConclusionThe data suggested that the administered doses had low toxicity. Nevertheless, concerns regarding reproductive toxicity remain because motility and sperm viability are negatively affected at the highest dose. Although bioinsecticides are widely used in organic food production, further research on each formulation, particularly regarding their long-term effects on organisms, is required.