Whereas the HIV prevalence in Guinea is among the lowest in Africa, many PLHIV in Guinea are malnourished. This study assessed the effect of a nutritional supplementation program on body mass index and CD4 count among adult PLHIV on ART. Study participants were PLHIV who came for consultation in the study sites between May and July 2016. The data came from two sources: retrospectively from participants’ medical records and interviews at the time of recruitment into the study. About six months before they were recruited into the study, some of the PLHIV started to receive a monthly nutritional supplementation consisting of Corn-Soy Blend and oil. Analytic methods included bivariate and multivariable methods. The intervention increased the mean BMI by 7.4% and the average current CD4 count by 4.7% compared to nonintervention (P<0.001). Programs in low resource settings should consider nutrition assistance as part of a comprehensive strategy to ensure optimal metabolic and immunological functions among PLHIV.