Abstract Background: Increased applications of quantum dots (QDs) in biomedical field have aroused attention for their potential toxicological effects. Although many studies have been carried out on the toxicity of QDs, their effects on reproductive and development are still unclear. In this study, we systematically evaluated the male reproductive toxicity and developmental toxicity of CdSe/ZnS QDs in BALB/c mice.Results: The male mice were injected intravenously with CdSe/ZnS QDs at the dosage of 2.5 mg/kg BW or 25 mg/kg BW, respectively, and the survival status, biodistribution of QDs in testes, serum sex hormone levels, histopathology, sperm motility and acrosome integrity was measured on Day 1, 7, 14, 28 and 42 after injection. On Day 35 after treatment, male mice were housed with non-exposed female mice, and then offspring number, body weight, organ index and histopathology of major organs, blood routine and biochemical tests of offspring were measured to evaluate the fertility and offspring health. The results showed that CdSe/ZnS QDs could rapidly distribute in the testis, and the fluorescence of QDs could still be detected on Day 42 post-injection. QDs had no adverse effect on the structure of testis and epididymis, but high-dose QDs could induce apoptosis of Leydig cells in testis at an early stage. No significant differences in survival of state, body weight organ index of testis and epididymis, sex hormones levels, sperm quality, sperm acrosome integrity and fertility of male mice were observed in QDs exposed groups. However, the development of offspring was obviously influenced, which was mainly manifested in the slow growth of offspring, changes of organ index of main organs, and the abnormality of liver and kidney function parameters.Conclusion: Our findings revealed that CdSe/ZnS QDs were able to cross the blood-testis barrier (BTB), produce no discernible toxic effects on the male reproductive system, but could affect the healthy growth of future generations to some extent. In view of the broad application prospect of QDs in biomedical fields, our findings might provide insight into the biological safety evaluation of the reproductive health of QDs.