OBJECTIVE: This study assessed general functioning in Nigerian adolescents with bipolar disorder. It also determined the factors associated with functioning in these adolescents. METHOD: Adolescents with bipolar disorder diagnosed over one year or more attending the outpatient unit of Federal Neuro-Psychiatric Hospital, Enugu (FNHE), Nigeria for follow-up visits were interviewed with a socio-demographic questionnaire and their functioning was rated with the Children Global Assessment Scale (C-GAS) based on the clinical information obtained from the children and their care givers during a one year follow-up period. Further information such as history of sexual risk behavior, pre-morbid peer relationship, relationship with siblings, level of religion activities among others were also obtained through clinical interview. RESULTS: A total of 46 adolescents with bipolar disorder were followed up. Minimal to moderate impairment in functioning in the past year was found in these adolescents. The mean score on C-GAS was 68.41 ± 16.63. Factors including co-morbidity, pre-morbid peer relationship, relationship with siblings, level of religion activities and history of sexual risk behavior were significantly associated with functioning (p = 0.000), while marital status of the parents showed a weak association with functioning in these adolescents (p = 0.068). Negative correlation was also found between mean number of hospital admissions in the past year during follow up and mean score on C-GAS (r = - 0.908, p = 0.000). CONCLUSION: Functional impairments complicate bipolar disorder in Nigerian adolescents. To ensure good overall outcome in these adolescents, attention needs to be focused on promoting those factors that help good functioning. Future longitudinal follow up studies that would assess long-term outcome and its correlates in children and adolescents with bipolar disorder in this environment are desirable.