The aim of current study was to assess the pattern of adverse drug reactions (ADRs) in patients receiving antiretroviral (ARV) therapy. A prospective observational study was conducted for 6 months from March to August 2018 at ART Centre, Sri Venkateswara Ram Narayan Ruia Government General Hospital (SVRRGGH) and Tirupati. This is a tertiary care teaching hospital. The study had taken the institution ethical committee approval. Data were evaluated for patient demographics, laboratory data, ART regimen and type of ADRs. CDSCO forms were used to record the ADRs. Causality, severity and preventability of ADRs were assessed by suitable scales. Out of 216 ADRs identified, majority were females (54.35%) followed by males (46.65%). The most common regimens which caused ADRs were Tenofovir +... Lamivudine + Efavirenz (55.55%) and Zidovudine + Lamivudine + Nevirapine (45.45%). Majority of ADRs fall between 31-40 years (35.64%) followed by 20-30 years (27.31%) of age. Most of the ADRs were related to CNS abnormality like abnormal dreams (27.31%), followed by lipodystrophy (26.38%), anaemia (23.14%), diarrhoea (12.96%), skin rash (9.25%), renal abnormalities (0.46%) and myopathy (0.46%). On evaluation of NARANJO’S causality of ADRs, majority were found to be probable (99.7%). The modified Hartwig and Siegel’s severity assessment scale showed that most of the ADRs were mild (64.42%). The modified Schumock and Thornton preventability scale showed that 50.92% ADRs were probably preventable. Adverse drug reactions of Antiretroviral are frequent and could be life threatening in short and long terms. Regular follow up of patients receiving the triple therapies by using assessment scales, early detection of ADRs to improve the medication adherence and to prevent permanent harm to the patients.