Background :Sepsis is a life-threatening organ dysfunction caused by infection and its rapid, accurate diagnosis is a huge burden. Renal failure induced by sepsis is still an exasperating problem in the clinical inquiry. Aim: This paper examines a new biomarker; serum procalcitonin (PCT) in the diagnosis of sepsis. PCT is a a calcitonin precursor secreted mainly from the thyroid gland. PCT efficacy in diagnosis of sepsis and the accompanying renal cell dysfunction by the expected successive apoptosis after sepsis were explored. Methods: 40 adult male albino rats were divided into: The control group: received intra‌peritoneal saline (IP) and LPS injected group: received 10 mg/kg of lipopolysaccharides (LPS), from Escherichia coli IP once. The rats were monitored using a mouse clinical assessment score (M-CASS) for 48 hours. Body temperature, blood pressure and serum glucose level ,leucocytic count , serum creatinine and urea and serum procalcitonin were estimated . Immunohistochemical staining of caspase 3-cellular expression in renal tissue.Results: increase mortility rate in septic rats. PCT was significantly increased in septic rats with high sensitivity and specificity. Significantly increased serum urea and creatinine, reduced blood glucose, and increased renal caspase 3 expression were exhibited in the LPS injected group. Tachycardia, hypotension and hypothermia were highly significantly increased in the LPS injected group. The behavioral changes were all detected after LPS injection. Conclusion: Serum procalcitonin is a noval, accurate and specific biomarker in the diagnosis of sepsis and its associated renal dysfunction, explained by increase in renal tissue caspase 3 expression.