A guideline on pelvic girdle pain (PGP) was developed by "Working Group 4" within the framework of the COST ACTION B13 "Low back pain: guidelines for its management", issued by the European Commission, Research Directorate-General, Department of Policy, Coordination and Strategy. To ensure an evidence-based approach, three subgroups were formed to explore: (a) basic information, (b) diagnostics and epidemiology, and (c) therapeutical interventions. The progress of the subgroups was discussed at each meeting and the final report is based on group consensus. A grading system was used to denote the strength of the evidence, based on the AHCPR Guidelines (1994) and levels of evidence recommended in the method guidelines of the Cochrane Back Review group. It is concluded that PGP is a specific form of low back pain (LBP) that can occur separately or in conjunction with LBP. PGP generally arises in relation to pregnancy, trauma, arthritis and/or osteoarthritis. Uniform definitions are proposed for PGP as well as for joint stability. The point prevalence of pregnant women suffering from PGP is about 20%. Risk factors for developing PGP during pregnancy are most probably a history of previous LBP, and previous trauma to the pelvis. There is agreement that non risk factors are: contraceptive pills, time interval since last pregnancy, height, weight, smoking, and most probably age. PGP can be diagnosed by pain provocation tests (P4/thigh thrust, Patrick's Faber, Gaenslen's test, and modified Trendelenburg's test) and pain palpation tests (long dorsal ligament test and palpation of the symphysis). As a functional test, the active straight leg raise (ASLR) test is recommended. Mobility (palpation) tests, X-rays, CT, scintigraphy, diagnostic injections and diagnostic external pelvic fixation are not recommended. MRI may be used to exclude ankylosing spondylitis and in the case of positive red flags. The recommended treatment includes adequate information and reassurance of the patient, individualized exercises for pregnant women and an individualized multifactorial treatment program for other patients. We recommend medication (excluding pregnant women), if necessary, for pain relief. Recommendations are made for future research on PGP.