Although valproic acid (VPA) is a low-cost and effective drug, it is known to cause organ toxicity via oxidative stress and related process. In present study, we aimed to evaluate the possible protective effects of thymoquinone (TMQ) on VPA-induced testicular toxicity. Male Sprague-Dawley rats were divided into three as control, VPA (500 mg kg(-1) day(-1)) for 14 days and VPA plus TMQ (50 mg kg(-1) day(-1) for 14 days) with seven rats in. Spermatic and interstitial degenerations induced by VPA were ameliorated with TMQ. In VPA group, increased TOS and OSI levels, and decreased TAS level were seen. TMQ reversed these oxidative stress parameters significantly. In Western analysis, VPA was found to increase the expressions of phospho-nuclear factor kappa beta (p-Nf-kB) and Caspase-3. These expressions were decreased by TMQ significantly. Intense immunostaining for p-Nf-kB, Caspase-3 and NADPH oxidase 2 induced by VPA were transformed to moderate immunostaining by TMQ. VPA-induced inflammation and apoptosis that were developed mainly by p-Nf-kB pathway were attenuated by TMQ. TMQ can be a candidate supportive treatment for patients who need long-term and high-dose VPA therapy. TMQ inhibits the Nf-kB activation, and in addition to antioxidant property, it shows anti-inflammatory feature on VPA-induced testicular toxicity.