The purpose of this study was to identify predictors of infection with Chlamydia trachomatis in order to suggest indications for culture among women in general practice. In a multi-practice study 29 general practitioners examined 352 women complaining of vaginal discharge and 225 women having a pelvic examination for other reasons. Information from patient history, pelvic examination, and laboratory tests was recorded, and a culture for C. trachomatis was performed. C. trachomatis was isolated from 30 women (8.5%) with complaints of vaginal discharge and from nine (4.0%) without complaints. The predictive value for chlamydial infection of the information obtained was examined by logistic regression. Complaints of vaginal discharge, age under 25 years, use of oral contraception, suspected exposure to sexually transmitted disease, increased amount of discharge on pelvic examination, pH of discharge above 5.0 and the presence of leucocytes on wet smear microscopy were predictive of infection with C. trachomatis. Using information from patient history alone it was possible to discriminate between patients with low and high risk for chlamydia infection, the range being from 2% to 37%. Indications for culture for C. trachomatis, based upon easily obtained information from the patient history, are suggested.