BACKGROUND: Attention-Deficit / Hyperactivity Disorder (ADHD) is one of the most prevalent behavioural disorder among children and adolescents with HIV infection (CA-HIV). OBJECTIVE: To explore the explanations used by adolescents with HIV/AIDS, caregivers and health workers to understand and explain ADHD in HIV/AIDS. METHODS: This was a qualitative sub-study nested within a larger research project whose focus was on mental health among HIV infected children and adolescents in Kampala and Masaka, Uganda (CHAKA study, 2014-2017). Participants were recruited from five study sites: two in Kampala and three in Masaka. We purposively sampled 10 ADHD adolescent-caregiver dyads equally divided between the Masaka and Kampala sites, age groups and gender. Semi-structured interviews were carried out within 12 months of baseline. Ten HIV health workers (two from each study site) participated. The ten health workers were assessed about their knowledge related to psychiatric disorders (especially ADHD in HIV/AIDS), services available for such clients and gaps in service provision for CA-HIV with behavioural / emotional disorders. Participants were recruited over one month. Taped interviews were transcribed and preliminary coding categories generated based on the research questions. Broad categories of related codes were then generated to derive a coding framework. Thematic analyses were conducted to elicit common themes emerging from the transcripts. RESULTS: Explanations used by respondents to express their understanding related to ADHD among CA-HIV included; psychosocial stressors, biomedical manifestations, personal traits and supernaturalism, which affected health seeking behaviour. CONCLUSION: In contexts similar to those in Uganda, treatment approaches for ADHD among HIV positive CA-HIV should consider the explanations provided by CA-HIV, caregivers to CA-HIV and HIV health workers.