Background: Forensic professionals have a crucial responsibility when estimating the postmortem interval (PMI), particularly in criminal situations. Drowning is a deadly asphyxiation incident brought by extended submersion in a liquid. Diagnosing death toll from drown remains the most complex challenge for forensic pathologists. This work aimed to determine drowning deaths in relation to PMI using histopathological changes and the expression of microRNA-23b-3p and microRNA-381-3p in brain and lung tissues. Methods: In this study, thirty adult albino rat models were used. Three groups were created out of them (0, 12, 24 hrs. after death), each of which contains 10 rats. Brain and lung tissues from each rat were taken out and divided into two pieces. The first was prepared for histopathological analysis, and the second portion was prepared for the analysis of microRNA expression by RT-PCR. Results: The brain tissues showed pyknotic nuclei of the neurons with mild vacuolation at the time of death, which progressed with an increased postmortem interval to marked vacuolation. While lung tissues showed overdistention of the alveoli, which became marked with an increased postmortem interval with marked dissolution of interstitial cells at 24 hrs  postmortem. MicroRNA-23b-3p and microRNA-381-3p levels showed a significant difference in brain and lung tissues at different postmortem intervals. Conclusion: MicroRNA-23b-3p and MicroRNA-381-3p expression could be helpful as new biomarkers for the determination of drowning death in relation to time since death.