Objective: Synthetic cannabinoid (SC) use has recently become a growing substance abuse problem, with serious harmful clinical effects. Young males, especially cannabis (C) users, are at great risk of SC use. The aim of this study is to determine sociodemographic characteristics, clinical features and serum liver function tests of SC users and compare with those of C users. Methods: Out of 118 SC users applied to outpatient clinic of Ankara Numune Training and Research Hospital Alcohol and Substance Addiction Treatment Center, 74 males included in this cross-sectional study. Patients with a concurrent use of any medication or substance other than C/SCs or patients with any physical illness which could affect serum liver function tests were excluded. 44.6% (n=33) of 74 patients were only SC users at least for last three months and 55.4% (n=41) were combined C and SC (CSC) users. SC users were compared with 34 age and BMI-matched only C using males. Results: Rates of being single and divorced; rates of living with friends and alone were found to be higher in SC users. Adverse effects and withdrawal symptoms were found to be similar in C users and SC users. According to serum liver function test results, levels of gama-glutamil transpeptidase, alkaline phosphatase, total/direct bilirubin, albumin, prothrombin time and international normalized ratio were similar. Serum aspartate aminotransferase levels (31.2±22.0 IU/L and 41.5±21.5 IU/L respectively, p=0.026) and serum alanine aminotransferase levels (28.4±18.9 IU/L and 44.3±25.9 IU/L respectively, p=0.015) differed between C users and C SC users. Results in this study revealed that increased serum levels of aminotransferases were especially associated with combined use of C and SCs. Conclusions: C abuse seems to be a precursor of SCs abuse, and risk of starting SCs use could be bigger for C users, who live alone or with friends, whereas living together with a family could be preventative. Combined use of C and SCs seem to increase the risk of hepatocellular injury compared to either C or SCs alone. [Anadolu Psikiyatri Derg 2017; 18(6.000): 543-551]