Infection with Human Immunodeficiency Virus (HIV) is a global burden affecting large population throughout the world. Regular monitoring of CD4 cell count and viral load is necessary to evaluate treatment success in patients undergoing antiretroviral treatment (ART). This study was carried out with the aim of determining the CD4 T-cell counts and viral load on patients in antiretroviral therapy. The cross sectional descriptive study was conducted on 175 HIV infected individuals on ART who visited at National Public Health Laboratory (NPHL), Teku, Kathmandu, Nepal for their viral load estimation.