Background: AMB-FUBINACA abuse was confirmed in case reports of a mass intoxication in the United States. Also it was reported that in New Zealand, there were at least 20 deaths related to the use of MMB-FUBINACA. Aim of the Work: To detect the toxic effect of synthetic cannabinoid (AMB-FUBINACA) with different doses on the testis of adult male albino rats histopathologically and Biochemically. Methods: the present work was conducted on 40 sexually mature male albino rats. Rats were divided into 5 groups 8 rats each as follow Group I: Negative control group, Group II: Positive control group where animals received ethanol 5%, Group III: Rats treated with AMB-FUBINACA at dose of 2.5 mg/kg dissolved in ethanol 5%, Group IV: Rats treated with AMB-FUBINACA at dose of 5 mg/kg dissolved in ethanol 5% and Group V: Rats treated with AMB-FUBINACA at dose of 10 mg/kg dissolved in ethanol 5% given by intraperitoneal injection for 4 weeks. Results: a significant decrease of testosterone level in AMB-FUBINACA treated groups compared to the control groups and degenerative changes in seminiferous tubules was also observed in treated groups. Conclusion: administration of AMB-FUBINACA for 4weeks was associated with toxic effects in testis