Cross sectional study was carried out in 32 cases of HIV infected patients on ART developing IRIS and attending Centre of Excellence(COE) RIMS and who were admitted to Medicine ward, RIMS Hospital. Duration of study was from October 2014 to September 2016. The study showed that IRIS was found mainly in the age group of 30-40 years and more common among patients with BMI of below 18.5 kg/m2 and paradoxical IRIS was more common than unmasking type of IRIS. Mean duration of development of IRIS was 87 days and the most common ART regimen in the study group was Tenofovir+Lamivudine+Efavirenz. Tuberculosis was the most common opportunistic infection and the mean baseline CD4 count at the time of initiation of ART was 167.5 cells/ μl. At the time of IRIS detection, the mean increase in CD4 cell count from the time of ART initiation was 86.66 cells/μl (Mean SD± 61.12cells/ μl. Tuberculosis was the most common opportunistic infection and paradoxical type of IRIS was more common than unmasking type.