BACKGROUND Anastomotic leakage is the most dreadful complication of colorectal surgeries. It results in sepsis, entero-cutaneous fistula formation, leads to reoperation and permanent stoma and is associated with decreased survival and death. The clinical presentation may not be evident in the initial phase, when a timely intervention may save the life of the patient or could avoid a reoperation or a permanent stoma. The current study is to evaluate the diagnostic efficacy of peritoneal drain fluid CRP to predict anastomotic leakage in elective colorectal surgeries. MATERIALS AND METHODS 50 patients with elective colorectal resection and primary anastomosis were studied. The selected patients were followed up from their preoperative admission in the ward till discharge. Demographic data of the patients, operative details, postoperative events and follow up data were obtained through a standardized case record form and were entered into a data base. In the postoperative period, drain fluid reservoirs were emptied 2 times a day within 12-hour intervals, under aseptic precautions. The evening collection was disposed off. CRP is estimated on postoperative day 3 and day 5. The values obtained were compared between the groups of patients without complications of surgery and in those with anastomotic leakage. RESULTS Clinically evident anastomotic leakage was observed in 7 patients (14%), in 3(6%) following right hemicolectomy and in 2(4%) following anterior resection and 2(4%) following left hemicolectomy. The mean value of CRP on postoperative day 3 was 48.41 in patients without anastomotic leakage and those with anastomotic leakage was 40.36 whereas, the postoperative day 5 CRP was 36.61 in patients without anastomotic leakage and 86.85 in those with leakage. On applying independent sample t test to day 5 CRP, it was found to be significantly elevated with a t value 9.45 and p value 0.001. To find out the cut off value of CRP in diagnosing those with anastomotic leak, an ROC curve was constructed. The area under the curve was 0.997 with a p value 0.001 and a confidence interval between 0.986 and 1.007. And it was found that with a cut off value of CRP 77.59, the sensitivity is 85% and specificity 100% in diagnosing anastomotic leakage. CONCLUSION Serial measurement of the drain fluid CRP can be reliably used in early detection of anastomotic leakage. It was found that CRP value on postoperative day 5 showed a progressive elevation from the day 3 CRP value. The mean CRP value on postoperative day 5 was 86.85 which is statistically significant with a sensitivity of more than 85% and with specificity of 100%.