There is considerable debate between the proponents of open and closed diagnostic peritoneal lavage (DPL). A prospective study was undertaken on 130 patients submitted to DPL. We performed 55 (42.3%) closed and 75 (57.7%) open lavages with sensitivity and specificity of 100 and 96.6% for the former and 92.2 and 100% for the latter. The mean time for insertion of the catheter and initiation of fluid infusion was significantly less in the closed DPL group, and so were the number of cases with prolonged procedures. No intra-abdominal or wound complications were detected with either method, but there were 10 DPL failures due to inability to conclude the procedure successfully and derive a definite result. Eight of these (10.6%) belonged to the open group and two (3.6%) to the closed (P < 0.05). Our findings suggest closed DPL is as equally sensitive and specific as closed DPL, but is more expeditious and offers inconclusive results less often. Both procedures are useful and should be parts of surgical training.