The aim of this study was to investigate p38-mitogene-activated protein kinase (p38-MAPK), nuclear factor-kappa B (p65-NF-kB) and inducible nitric oxide synthase (iNOS) expression in an experimental model of varicocele in the rat testis. Male Wistar albino rats (n = 18) were divided into three equal groups: control group, sham operated group and left varicocele-induced group. Malondialdehyde (MDA), nitric oxide (NO) and reduced glutathione (GSH) levels were biochemically assessed, and the p38-MAPK and NF-kB activity, and iNOS expression were immunohistochemically studied in the right and left testicles of rats from each group. The GSH levels were significantly decreased, whereas the level of MDA and NO was significantly increased in the testicular tissues of rats in varicocele group compared with those of the control and sham groups. There was a marked staining for iNOS, p38-MAPK and p65-NF-kB expression in rats of varicocele group compared with the sham group. There was no positive staining in rats of control group. There were significant differences in biochemical, histological and immunohistochemical studies, but no significant differences were noted between other groups. p38-MAPK and p65-NF-kB activation, and iNOS expression have a significant role in varicocele-induced testicular dysfunction.