Nanoscale graphene oxide (NGO) has great potential in biomedicine by the virtue of its facile functionalization and tunable characteristics. Toxicity assessments have, therefore, become essential prior to its biomedical applications. The present study examined the effects of NGO exposure on male reproductive function of adult Wistar rats. Rats were exposed intraperitoneally to three increasing doses, namely low (0.4 mg/kg BW), mid (2.0 mg/kg BW) and high (10.0 mg/kg BW) dose of NGO. Repeated exposure of NGO for 15 and 30 days resulted in decreased epididymal sperm counts and elevated sperm abnormalities. Percentage of motile sperms was also significantly reduced due to the exposure. Activities of SOD, GPx and malondialdehyde concentration in testes increased in a dose-specific manner. Results of the study demonstrated that high-dose NGO (10.0 mg/kg BW) resulted in considerable histological damage to testicular tissue which included atrophy of seminiferous tubules with reduction in germinal epithelium, germ cell loss and vacuolization. Low and mid doses of NGO were not associated with sperm dysfunction or testis damage. Withdrawal of treatment for 30 days demonstrated significant recovery potential. Histology of epididymis and male fertility potential were not affected due to the NGO exposure. These findings are important for assessment of the risk involved in manufacturing, use and processing of the graphene oxide-based materials towards male reproductive function. This article is protected by copyright. All rights reserved.