BACKGROUND The sphincter of Oddi regulates both bile and pancreatic juice flow into the duodenum. When dysfunction occurs it leads to problems relating to either the bile or pancreatic ducts. On the biliary side, the most common problem is recurrent biliary type pain following cholecystectomy. OBJECTIVE Is sphincterotomy effective treatment for biliary sphincter of Oddi dysfunction patients? METHODS Electronic data bases, including the Collaborative Review Group trial registers, MEDLINE, and EMBASE, as well as checking reference lists in as many languages as possible that had the titles: sphincter of Oddi dysfunction, biliary dyskinesia, papillary stenosis, biliary dyssynergia, odditis, papillitis, post-cholecystectomy pain, right upper quadrant pain, or unexplained right upper quadrant pain were included. These titles were matched with sphincterotomy. METHODS Randomised placebo-controlled trials performing sphincterotomy in patients with suspected biliary sphincter of Oddi dysfunction using manometry as part of the patient evaluation. A basal pressure > 40 mmHg was defined as abnormal. The primary outcome measure were symptomatic response (defined either as cure/improvement or not improved) to sphincterotomy. METHODS Electronic data bases were used to search for the studies. Studies were attempted to be stratified as randomised clinical trials, controlled clinical trials (i.e., quasi-randomised clinical trials), well designed observational studies using a well matched control group, or other. These groupings were then entered into a meta-analysis. RESULTS Only two randomised clinical trials met the inclusion criteria. In 49 patients studied, sphincterotomy was more effective than placebo in treating patients with an elevated basal pressure (Peto odds ratio 9.08, 95% confidence interval 2.97-277.77). In 77 patients studied, sphincterotomy was no better than placebo in treating patients with a normal normal basal pressure (Peto odds ratio 1.28, 95% confidence interval 0.52-3.13). There was no data on quality of life or health economics. CONCLUSIONS These results suggest that sphincterotomy for biliary sphincter of Oddi dysfunction appears effective in those patients with an elevated sphincter of Oddi basal pressure (>40 mmHg), but is no better than placebo in those patients with a normal basal pressure. The results reported in this review must be interpreted with caution as there are only two studies and one of the reviewers (Toouli) has been an author in both studies. Further trials by independent groups are recommended.