Background: The estimation of time since death by whatsoever means or methods relies on changes that occur in the body after death. The changes in morphology of white blood cells are also variable depending on different factors, like other parameters used for the purpose of determination of TSD but it is less variable as compared to others. In this present study, morphological cellular changes of leukocytes had been taken into consideration, being compared with the changes with post mortem interval,  these degenerative changes is being discussed here in this study. Type of Study: It’s a cross sectional study. Material & Method: This prospective study was carried out at department of Forensic Medicine in collaboration with department of Pathology at Kamineni Institute of Medical Sciences, Narketpally January 2014 to December 2014. Observation and Discussion: In Lymphocytes identifiable degenerative changes began after 24 hours for both the group, Lymphocytes showed degenerative changes even after 84 hours, but could be easily identified even after that period. Lymphocytes nuclear swelling and indistinctness in cytoplasmic cell membrane were observed after 24 hour, while pyknosis, nuclear fragmentation and disintegration were observed after 36, 72 and 96 hour respectively. Lymphocytes were still identifiable after 120 hour and later observed in H Doghoz study. Conclusion: The present morphological observations suggest that the lymphocytes are most resistant blood cells to autolytic changes, the Eosinophils and Monocytes are intermediate and Neutrophils are affected early. Considering the application of these cellular changes to estimate time since death, it can be said that the result discussed thus far seems to lead disparate conclusion.