Background: Inadequate adherence in Acquired immunodeficiency syndrome (AIDS) increases the risk of drug resistance and treatment failure. Adherence is a serious challenge for those receiving Anti–Retroviral Therapy (ART) especially children. Factors associated with pediatric ART adherence can be related to caregivers, children themselves, the medication/regimen, socioeconomic, or service delivery issues. Objective: The present study was conducted to know the factors affecting adherence to ART in pediatric HIV/AIDS patients at tertiary care hospital. Methods: The study was a hospital based cross – sectional study where 216 children registered at the pediatric ART clinic of a tertiary care hospital in Delhi and their caregivers were included in the study. Semi–structured, pretested interview schedule was used for data collection through face to face interview. Results: Out of the 216 children, males outnumbered females in the ratio of 2.48:1. Approximately 90% of the study subjects had ≥ 95% adherence in last 3 months of the study. Independent risk factors in multivariate logistic regression analysis for non–adherence were: lower age of the child, female gender, non–parental caregiver and presence of illness in last six months. Conclusion: Factors associated with non–adherence to ART were lower age, female, non–parental caregiver and presence of illness.