Background: A major concern with scaling up of antiretroviral treatment in resource limited settings is the emergence of drug resistant viral strains due to sub optimal adherence. CD4 count is also used as proxy measure to assess the level of adherence. Objectives: To study the level of adherence and to know the CD4 response in relation to adherence. Methods: A cross-sectional, observational study conducted using a semi structured and pre-tested questionnaire on 270 PLHA receiving ART. PLHA were interviewed from 1st Dec 2008 to 31st Jan 2010, at an integrated positive prevention clinic at tertiary care hospital. Adherence was assessed on self report over a period of 3 months. CD4 count was taken from the records Statistical analysis: Proportions, Chi-square test, z test using Microsoft excel Results: The mean age for PLHA was 36 years. Majority were females (55%). 79% (213) were adherent over previous one week recall and 84% (227) were adherent over previous 4 days. Adherence increased over longer period of recall. The mean CD 4 count of adherent group was 438.8 cells/mm3 and that of non adherent group was 332.3 cells/mm3 , the difference was statistically significant. Mean change in the CD4 count was increased as the duration of treatment with ART increased in adherent group. Conclusion: Level of adherence found was low hence adherence issues should be addressed during counseling of PLHA. Study indicates that better adherence leads to better immunological outcome.