BackgroundThe testis is the male reproductive gland or gonad having two vital functions - to produce both sperm and androgens, primarily testosterone.PurposeThe study aimed to investigate the effect of tramadol and boldenone injected alone or in combinatio for 2 months in rats on testicular function.MethodsGroup 1; normal control, Group 2; tramadol Hcl (TRAM) (20 mg/kg bwt.) (i.p). Group 3; boldenone undecylenate (BOLD) (5 mg/kg bwt) (i.m). Group 4; combination of TRAM (20 mg/kg bwt.) and BOLD (5 mg/kg), respectively for 2 months.ResultsTRAM and BOLD alone and in combination rats showed deteriorated testicular functions, lowered serum steroid levels (FSH, LH and testesterone), elevation in oxidative biomarkers (MDA & NO) and reduction in GSH and SOD, downregulation of StaR and HSD17B3 as well as assessment of testicular histopathological using H&E staining, PAS stain for histochemical assessment of polysaccharides and glycoproteins in the testes and Masson trichrome stain to assess the changes in the collagen fibers.ConclusionThe study illuminated the hazard of administration of these drugs for a long period as well as the prominent deleterious effects reported on concurrent use of both drugs.