摘要：Indroduction: National Aids control Organisation in India implementing National AIDS control?program uses WHO’s immunological criteria to screen virological failure. Using immunological criteria to detect virological failure has to be assessed. Predicting virological failure with immunological criteria in resource limited settings had low sensitivity. Factors that influence the outcome are studied. Methods: Retrospective study in tertiary care centre for HIV and TB, Chennai, India. Out of 35,044 on ART between January 2008 and September 2009, 452 suspected immunological failures were referred. 273 screened for virological failure.?Frequency, sensitivity/specificity, positive/negative predictive values, chi-square test, odds-ratio, independent sample t test for viral load greater than 10,000 and 1000 of each immunological criterion using Epi-Info and SPSS version 19. Results: 172 had virological failure (62.09%). Average age of failed was 37.33. Single criteria’s sensitivity was 60 to 84 for detecting virolological failure. Two or more criteria had specificity 55 to 79. Combination of two or more criteria increased odds ratio for virological failure. Positive predictive value was above 63 for all criteria. PPV was above 80 to the criterion all three positive. Conclusions: ART naive patients with >95% adherence the sensitivity of immunological criteria to detect virological failure is three times than earlier studies. Combination of criteria is more significantly associated with virological failure. Odds ratio doubled for two or more combination of criteria. Immunological criteria is affordable/acceptable for screening virological failure, with adherence > 95% and longer the duration of ART.