BACKGROUND Previous studies have suggested that pathological gambling and substance abuse may be more likely to occur together than expected by chance. We examined this possibility as well as explored psychosocial and diagnostic variables that may be associated with this coincidence. METHODS Of 276 patients who were administered the South Oaks Gambling Screen, 134 subjects were interviewed using a semistructured comprehensive psychiatric questionnaire. Data analysis utilized Student t tests or analysis of variance routines. RESULTS The rate of comorbid pathological gambling in the sample was 33% (92 of 276). A high rate of comorbid substance abuse and pathological gambling was associated with a positive history of childhood experiences of gambling in the family group (p = .001) and with larger family size (p = .001). In addition, current alcohol consumption was significantly higher (p = .007) in the pathological gambling group. CONCLUSIONS Comorbidity of substance abuse and pathological gambling is common in substance abuse patients in a VA hospital. Substance abuse treatment programs should identify patients with pathological gambling and include treatment interventions that address both problems.