Aims: To determine adherence levels to Isoniazid preventive therapy (IPT) and the factors influencing it in people living with HIV (PLHIV). Materials and Methods: An institution based descriptive longitudinal study was conducted from September 2017 to June 2019 to assess the level of adherence to IPT and its determinants among HIV patients. A total of 320 participants were included from the associated ART centres. Adherence was defined as completion of the 6-month course of treatment with 80% pills taken and was measured by self -report of intake of tablets. Proforma and a semi-structured questionnaire was used to collect all the relevant information. Questionnaire covered aspects on TB treatment and care, HIV related stigma, medical provider relations, social support and socioeconomic status. Data was analysed using SPSS version 11.5. Results/ Discussion: IPT Adherence rate was 83.75 %. Of the 320 patients, 268 were adherent. Isoniazid related side effects were reported by 50 people, 33 of whom were withdrawn. Prior history of TB was noted in 43 people. Patients cited counselling and physician’s advice on IPT intake as one of the main reasons for good adherence. Forgetfulness was the most common reason for missed pills.