HIV infection is characterized by gradual deterioration of immune function mainly the CD4 cells. This study was conducted with the objectives to evaluate the kinetics of CD4 cell depletion and duration of HIV infection and the role of ART in improving CD4 cell levels specifically in Nepalese HIV patients. During April 2005 to March 2006, all together 220 blood samples collected from 110 HIV patients visiting National Public Health Laboratory (NPHL), Kathmandu, were analyzed for CD4 cell count using standard protocol. CD4 cell count before and after starting of anti-retro viral therapy showed significant association (P<0.05). The results of this study clearly indicated that antiretroviral therapy has been playing a role in maintenance CD4 cell counts in HIV infected patients.