Introduction:
In Nigeria, non-adherence to treatment or its interruption endanger successful human immunodeficiency virus (HIV) control. This study identified the causes and prevention of defaulting from antiretroviral therapy (ART) among adults on ART at Federal Medical Centre, Owo, Ondo State, Nigeria.

Material and methods:
To explore the  perspectives, thoughts, behaviors of  respondents, and new ideas, qualitative information was collected using focus group discussions (FGD) guide and in-depth interviews (IDI) guide. IDI of defaulters and FGD with persons compliant with treatment were conducted to identify the barriers to retention in care and its prevention. Data were transcribed and analyzed using the thematic framework approach.

Results:
Reasons for defaulting included traveling out of place of residence, lack of support from employer, failure to disclose HIV status to partner and caregivers. Both FGD and IDI revealed poverty/ unemployment, pill fatigue, religious factors, lack of family support, family problems, and stigmatization/discrimination, as the major reasons for defaults. Results from the FGD suggested strengthening of counselling sessions and improved follow-up to reduce defaulting.

Conclusions:
Encouraging clients to access care in health facilities, which are near their places of residence will reduce the cost of care and improve the treatment and care. Introduction of Saturday and Sunday clinic days, with options of evening visits in the evening, will promote adherence to treatment.