Diagnostic peritoneal lavage (DPL) is an accepted method for evaluating patients with suspected intra-abdominal injury, especially in those with blunt abdominal trauma for whom early operative intervention may be life-saving. To evaluate this method in blunt abdominal trauma victims, we prospectively studied 2010 patients with blunt abdominal trauma who underwent DPL between 1978 and 1996 in our emergency department (at the regional tertiary university medical centre). The patients were then divided into three groups based on their DPL results. Of the total of 2010 patients, 719 (35.8%) met the criteria for positive DPL, indicating the need for laparotomy; 1213 (60.3%) had a negative DPL; and the remainder (78 patients, 3.9%) had equivocal DPL results. All the patients with positive DPL underwent emergency laparotomies which were therapeutic in 547 (76.1%) and non-therapeutic in 156 (21.7%) who had intra-abdominal haemorrhage. Sixteen patients out of 719 (2.2%) had no organ injuries in explorative laparotomy. When the 2010 cases in this study were evaluated, overall rates of specificity, sensitivity and positive predictive rates were found to be 87.3%, 96.3% and 76.1% respectively; the false positive rate was 23.9%, the false negative rate 1.8% and the negative predictive value 98.2%. Complications related to DPL developed in 31 patients (1.5%) out of the 2010 undergoing DPL. It is evident from the results that DPL is a reliable method. However, the criteria for positive DPL should be re-assessed based on the fact that the method itself had a false positivity rate of 23.9% leading to unnecessary operations.