Diatoms are unique and single celled algae belonging to the family Bacillariophyceae. They are the rarest found algae in the water. Diatom plays important role in the prognosis of deathin drowning. Diatom present in tissue indicates the sign of drowning. The utility of diatom for the identification of death cases due to drowning was discussed soon after they were found inlungexudates. For diagnosis of diatom, hard bone and soft tissue of dead bodies found in water are often sent to Forensic Science Laboratories. Dissolution of evidence is not very difficult but the complete removal of these diatoms frustules from the evidence needs great care, protection, more attention, and expertise. During analyze of drowning cases a connection between the diatomextracted from the tissue sample and the sample obtained from the put at ivedrowning medium has to be confirmed for the successful resolution of the drowning site. As aresult a proper procedure for the extraction of diatom from the tissue and water evidence to keep away from even minor contamination. Diatom examination has been suggested to provide supportive evidence of drowning. The same type of diatoms is found in almost similarty pes of water bodies. Significant changes in diatom diversity were found with seasonal changes. The quantitative distribution of diatoms in water sources is strongly assisted by climatic conditions.