The purpose of this study was to estimate the prevalence of psychiatric and personality disorders among industrial workers with substance use disorders and to investigate the association between this comorbidity and drug-related problems. A total of 353 industrial workers were included in the study. Sociodemographic and clinical data were collected from participants. Compared to controls, workers with substance use disorders were about 19 and 8 times more likely to have psychiatric and personality disorders, respectively. Anxiety (35.4%) and mood disorders (29.2%) were the most common psychiatric disorders among substance use workers. The most common personality disorders among substance use workers included antisocial and borderline (24.6% and 16.9%, respectively). There was a significant association between drug-related problems/dependence and psychiatric (χ2 = 14.04; p < 0.001) and personality disorders (χ2 = 18.74; p < 0.001). Psychiatric and personality disorders are common among substance use workers and are associated with drug-related problems.