In this study, the protective effect of Morinda citrifolia (Noni) against 3-methyl-4-nitrophenol (PNMC) toxicity in rat testes was investigated with an experimental period of five days. Fifty-six adult male Sprague-Dawley rats were allocated into seven experimental groups and a control (n: 7). One group received only Noni. Testicular tissue injury of six experimental groups was induced by subcutaneous injection of PNMC at three different doses (1, 10 and 100 mg/kg) and three received Noni treatment (2 ml per rat by gavage). On day six all rats were sacrificed and then blood samples and testis tissues were collected. Serum testosterone, FSH and LH levels were assessed. Testicular tissues were evaluated histomorphometrically in terms of tubular diameter, seminiferous epithelium density, luminal space and interstitial tissue and immunohistochemically labelled with inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) markers to assess oxidative damage. Histomorphometrically, most severe tissue injury was observed in the group of 10 mg/kg PNMC. Tissue injury improved significantly in its corresponding treatment group (with Noni). iNOS and eNOS levels increased in all PNMC groups and decreased with Noni treatments. Noni was most effective in the group of 100mg/kg PNMC in terms of oxidative damage. Serum hormone levels revealed no significant results. In conclusion, Noni reduced PNMC-induced tissue injury in rat testes.