BACKGROUND AND AIMS: Diabetes mellitus (DM) may have different adverse effects on the male reproductive system. Zinc (Zn) is one of the necessary elements in the human and mammalian diet that plays an important role in scavenging reactive oxygen species (ROS) by providing antioxidant and anti-apoptotic properties. The aim of this study was to determine the protective effects of zinc supplements on sperm chromatin and the evaluation of sperm deoxyribonucleic acid (DNA) integrity in diabetic men. METHODS: In this interventional study, 43 infertile Iranian men in diabetic and non-diabetic groups were included. They were then randomly divided into two subgroups: normal saline intake and zinc sulfate intake (25 mg orally for 64 days each). Different indices of sperm analysis (number, morphology and motility) and testosterone levels were evaluated in four groups. Protamine deficiency and DNA fragmentation were assessed using chromomycin A3 (CMA3) and sperm chromatin dispersion (SCD) methods, respectively. RESULTS: Zinc supplementation reduced the deformity of neck and head of sperms ( < 0.05), as well as deformity of sperm tail in infertile diabetic men. Zinc administration ameliorated sperm motility types A, B and C ( < 0.05). Moreover, zinc administration reduced abnormal morphology and DNA fragmentation of sperms, which increased the SCD1 and SCD2 and reduced the SCD3 and SCD4 in both treated groups. CONCLUSION: Zinc supplementation, as a powerful complement, is able to balance the effect of diabetes on sperm parameters, sperm chromatin and DNA integrity. Consequently, zinc supplementation can probably be considered a supportive compound in the diet of diabetic infertile men.