Background: The most prescribed anabolic steroid in gym practice is nandrolone decanoate (ND). It is implicated in sport doping, and criminal circles where personal aggressiveness was evident. Despite its wide use among athletes, its uncontrolled utilization causes serious toxicities of body organs. Taurine is an amino acid that is used as a supplement for bodybuilders and has many cytoprotective properties. Aim: This study aimed to evaluate the role of taurine in attenuation of the toxic effects of ND on biochemical parameters, histopathological and immune-histochemistry changes of hippocampus, heart and testis in adult male albino rats. Materials and Methods: It is an in vivo experimental study where 40 rats were classified into four groups; Control group, Taurine-treated, ND-treated group, and ND+Taurine group. Testicular levels of MDA, SOD, and TNFα, in addition to serum level of CK-MB were measured. Gene expression of testicular BAX, BCL2, MMP-9, Caspase-3, Cyp11a1, and hippocampal Prodynorphin were assessed. Hematoxylin and eosin (H&E), Masson trichrome stainings, immunohistochemical analysis and histo-morphometric studies were also done. Results: Taurine coadministration with ND significantly decreased levels of testicular MDA, TNF-α, serum CK- MB, and mRNA expression of testicular BAX, MMP-9, Caspase-3 and hippocampal Prodynorphin, with significant increase of testicular SOD level, and mRNA expression of testicular Cyp11a1 and a non-significant increase of testicular BCL2. The histopathological findings revealed marked amelioration of testicular and hippocampal toxicity, and significant decrease in collagen fibers in heart. Also, immunohistochemical expression of Ki-67 was increased in testis with decreased expression of GFAP in hippocampus comparable to ND- treated group. Conclusion: Taurine reduced the toxic effects of ND primarily on both the testis and hippocampus, in addition to a partial improvement in the heart. Keywords: Taurine; Nandrolone Decanoate; Testicular Toxicity; Cardiotoxicity; Neurotoxicity; Prodynorphin Gene Expression.