Background: Alcohol and substance use are important factors in criminal behavior and in reoffending. In this study, we looked at pattern and predictors of substance use among a population of prisoners in Nigeria. Methods: This is a cross-sectional survey involving prisoners at the Abeokuta maximum security prison. Participants were recruited using a simple random sampling; and based on their prison status i.e. either awaiting trial or convicted inmates. Alcohol and Substance Use Disorders were evaluated using structured clinical interview- the M.I.N.I. Plus. Diagnoses were based on the Diagnostic and Statistical Manual of Mental disorders- fourth edition (DSM-IV). Data were analyzed with SPSS-16 software and frequency, Chi-square, t-test were calculated as appropriate and logistic regression model was used to explore the relationship of other variables with alcohol and cannabis use disorders. Results: The mean age of prisoners was 34.77 ± 10.28. Alcohol and cannabis use disorders were the commonest form of substance use disorders with a lifetime prevalence of 29.5% and 18.1% respectively and current use disorder of 5.4% and 8.7% respectively. Significantly, alcohol use disorder was predicted by Fathers cannabis use, and the use cannabis while in the prison. Cannabis use disorder on the other hand was significantly predicted by parental marital status and the age at which the inmate left home, fathers’ cannabis use, lifetime AUD and current AUD. Conclusions: Despite the fact that prison is a confined environment, quite an appreciable number of prisoners still have access to alcohol, cannabis and other illicit substances with an appreciable number presenting with varying severity of substance use disorders. Alcohol and cannabis use disorders were found to be predicted by patients’ socio-demographics and drug use variables.