摘要:Background and Objective: Patients with Human Immunodeficiency Virus (HIV)/Acquired Immunodeficiency Syndrome (AIDS) infection experiences deficiency of vitamin D and abnormality of hematological parameters related to inflammatory and thrombotic activities. This study was designed to determine the relationship between changes in hematological parameters and vitamin D in HIV/AIDS infection. Materials and Methods: A cross-sectional study was conducted on 70 HIV/AIDS patients consuming Efavirenz (EFV)-based Antiretroviral Therapy (ART) for less than 6 months. Parameters including 25-hydroxy-vitamin D [25(OH)D] level and complete blood count. All parameters were measured in the Special Treatment Center (Pusat Pelayanan Khusus, Pusyansus) of the Voluntary Counseling and Testing (VCT) Clinic at Rumah Sakit Umum Pusat (RSUP) Haji Adam Malik, Medan, Indonesia. Results: There was a significant difference in terms of platelet count [mean±standard deviation: 329531.25 (79175.99) μL1 vs 282710.53 (69895.25) μL1, p = 0.011], Mean Platelet Volume/Platelet count (MPV/PLT) [Median (Interquartile Range): 2.86×105 (1.70×105-5.06×105) vs 3.27×105 (1.94×105-10.0×105), p = 0.022] and plateletcrit (PCT) [mean±standard deviation: 0.29 (0.08)% vs 0.25 (0.06)%, p = 0.018] in the group with 25(OH)D level of <21 ng mL1 compared to the group with 25(OH)D level of ≥21 ng mL1. There was a significant difference in terms of platelet count between the vitamin D sufficiency and insufficiency groups [mean±standard deviation: 300166.67 (71387.33) μL1 vs 274653.85 (69095.84) μL1, p = 0.036]. A significant difference was found in terms of platelet distribution width (PDW) between the vitamin D deficiency and insufficiency groups [mean±standard deviation: 9.02 (1.14)% vs 9.48 (1.03)%, p = 0.020]. Conclusion: Low level of vitamin D significantly correlated with platelet index in HIV/AIDS patients consuming EFV-based ART.