Background: Adherence to highly active antiretroviral therapy (HAART) has been proven to be the only effective treatment for HIV/AIDS worldwide. Good adherence to HAART might require good family support. Objective: To determine the family dynamics and social support of people living with HIV/AIDS (PLWHA) and its roles on HAART adherence at an ARV treatment clinic in Osogbo, Nigeria Method: Descriptive cross-sectional study. Consenting PLWHA on HAART were interviewed using pre-tested semistructured questionnaire incorporating Perceived Social Support- Family Scale and Family APGAR. HAART adherence was measured using patient self report. Results: A total of 379 PLWHA were interviewed. Their mean age was 40.8 (SD=9.9) years. Most (60.7%) were females. More than half (55.7%) were currently married and the majority (72.1%) had secondary education and were Yoruba (86.3%). Most respondents (95.5%) were adherent to HAART. Over 90% were satisfied with support received from their family while 82.3% were treated like other family members. Most attributed their HAART adherence to the care and support received from their family. Conclusion: Most PLWHA had good social support and were adherent to HAART.