In forensic medicine, estimating the postmortem interval (PMI) is of great importance for the timeline and the reconstruc-tion of the events surrounding death. Bone marrow (BM) is one of the largest organs in the body, with good resistance to autolysis and contamination. Therefore, the present study aims to correlate different postmortem intervals and bone marrow antioxidant enzyme levels using an Enzyme-linked immunosorbent assay (ELISA). In addition, detection of the changes in the histological structure of human bone marrow in relation to the time passed since death. BM samples from 20 forensic autopsy cadavers were obtained from cases referred to the Department of Forensic Medicine in the Ministry of Justice, Dakahlia Governorate, processed for histopathological examination as well as estimation of reduced glutathione (GSH), glutathione peroxidase (GPX), and glutathione reductase (GRX) using ELISA. Results of ELISA analysis showed a sig-nificant decrease in the level of antioxidant enzymes with increasing PMI; regarding histopathological examination, from 6 to > 18 h PMI, the changes in morphology after death were gradual, progressive, and regular, indicating great value in PMI determination. Also, 18 h of PMI showed loss of cellular details, absence of fat cells, and necrosis of BM with the nucleus dispersed as eosinophilic debris. Estimation of antioxidant enzymes level in human bone marrow using ELISA and detection of the changes in the histological structure of human bone marrow in relation to time passed since the death, either separately or in combination, can be used to estimate PMI accurately.