AIM To assess the functional impairment of young adults with bipolar disorder with substance abuse/dependence comorbidity. METHOD Cross-sectional study within a community sample. Bipolar Disorder was assessed by qualified psychologists using The Mini International Neuropsychiatric Interview - PLUS (MINI-PLUS). Substance abuse and dependence was assessed using the "Alcohol, Smoking and Substance Involvement Screening Test" (ASSIST). Functional impairment was assessed using the Functional Assessment Short Test (FAST). RESULTS The sample included 1259 young adults. The prevalence of Bipolar Disorder (BD) without Substance Abuse/Dependence (SAD) comorbidity was 5.9% (n=74), and the prevalence of bipolar disorder with substance abuse/dependence comorbidity was 1.4% (n=17). Both groups showed higher impairment in overall functioning, interpersonal relationship, and leisure time as compared to controls. In addition, BD+SAD showed higher impairment in the cognitive functioning domain of FAST. LIMITATION A battery of neuropsychological tests was not performed. CONCLUSION Functional impairment is associated with BD, independently of substance abuse or dependence. In addition, BD+SAD present a more severe impairment in the cognitive domain of FAST as compared to controls.