There is no accurate predictor of complications following open appendicectomy. Surgical impression, histological findings and peritoneal culture swabs have been used. The value of peritoneal culture swab was assessed in this study. All patients undergoing open appendicectomy between January 2003 and December 2005 were included in the study. During the 24-month period, 952 patients underwent open appendicectomy. Peritoneal culture swabs were taken from 309 patients (32%). There was a significant difference in the mean postoperative length of stay +/- SEM between those with a positive culture (7 days +/- 0.6), those with a sterile culture result (3.7 days +/- 0.2) and those on whom a culture swab was not taken (4.9 days +/- 0.3); p<0.0001, ANOVA. Surgeons were more likely to overcall the severity of the appendix pathology (p < 0.0001 surgical vs. histological findings; Fisher's exact test), however, there was no significant difference in the power of surgical or histological assessment of the appendicitis at predicting a positive peritoneal culture result. Complex appendicitis was more likely to be associated with a positive peritoneal culture (P < 0.0001; Fisher's exact test). No antibiotic regime was changed on the basis of a positive culture swab. Fifteen patients were readmitted within 6 months of appendicectomy, predictors of readmission included histologically confirmed complex appendicitis and a positive peritoneal culture swab. Peritoneal culture swabs do not improve immediate postoperative therapy based on surgical impression and rapid histological reporting, however, the routine use of peritoneal culture swabs may be of value in identifying patients requiring outpatient follow-up.