Introduction: Probiotics are live microorganisms that, when administered in appropriate colonies, can delay the destruction of the immune system and contribute to the maintenance of immunity in HIV patients. Probiotics play an important role in stimulating natural killer T cells, strengthening the functional gut barrier, and reducing systemic inflammation. Methods: This study was a randomized double blind clinical trial involving 30 patients treated with ART who had experienced immunological failure despite HIV viral suppression. Patients were divided into two equal groups of 15, the first group received 2 probiotic capsules daily with a colony count of 10⁹CFU per capsule containing seven strains ,after three months they were examined for CD4+ counts by flow cytometry, after a one month washout period the participants who had received probiotics were switched to placebo, and the participants who had received placebo were given probiotics for three months, and they were examined for CD4+ counts seven months after the start of the study. Results: In the first group, administration of the placebo resulted in a decrease in CD4 count in the first three months (from 202.21 to 181.79, p-value < 0.001),which may be due to the natural history of the disease. After probiotics administration, CD4 count increased significantly (from 181.79 to 243.86, p-value < 0.001). Overall, after 7 months of study, there was a significant increase in the mean CD count from 202.21 to 243.86 (p-value < 0.001). In the second group, administration of probiotics in the first three months of the study resulted in a significant increase in the mean CD4 count (from 126.45 to 175.73, p-value < 0.001).Termination of treatment with probiotics resulted in a significant decrease (from 175.73 to 138.9, p-value < 0.001)but overall the CD4 count at the end of the study was significantly higher than at baseline (p-value < 0.001).