Determination of time of death from postmortem changes such as cooling and rigor mortis will be less accurate by progression of postmortem interval (PMI). So, there is another method for estimation of time of death which can withstand putrefactive changes, such as biochemical analysis of body fluids. Aim: this study was done for estimation of time passed since death by analysis of synovial fluid parameters urea, creatinine, sodium (Na), potassium (K), calcium (Ca), chloride (Cl), and glucose. Methodology: Twenty-six cadavers were examined at postmortem interval: 6-12h, 13- 18h, and 19-24h. Results: The results of biochemical analysis in different PMI revealed that urea and Na levels had insignificant change. Each creatinine, Cl, and Ca showed significant change and weak correlation with time lapsed, but the correlation with glucose was moderate. Conclusion: measurement of glucose + chloride followed by glucose alone in synovial fluid may be helpful in determination of PMI.