Introduction: Dating burn injury in humans remains a challenging issue in forensic medicine. T-lymphocytes have a fundamental role in the healing process of burn injury. The study aimed to characterize time-dependent changes in T-Helper lymphocytes (CD4+) and T-Cytotoxic lymphocytes (CD8+) in human blood following thermal injury and to elucidate their accuracy in dating dry burn injury. Patients and Methods: This cross-sectional study included adult patients, admitted with second and /or third-degree dry burn with a total body surface area ranged from 10% to 50%. Ten eligible patients were recruited independently at the 1st, 3rd, 7th, and 15th days following burn injury. Additionally, ten matched healthy subjects served as a control group. Besides the patient's information, blood samples were withdrawn from each participant for flow cytometric analysis of CD4+ and CD8+ T-cells. Results: Percentages of CD4+ and CD8+ cells, and CD4+/CD8+ ratio exhibited a significant reduction in burnt patients compared to the control group throughout the first-week after-burn. Additionally, there was a significant time-dependent decline between the 1st, 3rd, and 7th days, following the burn. Receiver operating characteristic (ROC) analysis for these markers revealed a significant-excellent power of discrimination of burns aged less than 3 days (area under the curves were ≥0.9). Conclusion: It could be concluded that CD4+ and CD8+ T-cells in the human blood exhibited time-dependent changes after dry burns. They could help in dating acute dry burns in living humans with great accuracy, whatever the extent of burn injury.