Study Design. A prospective cohort study on low back pain in consecutive patients in general practice, in which potential prognostic indicators at baseline and at the 1-year follow-up examination were assessed by means of four weekly questionnaires. Objectives. To identify prognostic indicators of the duration of low back pain in general practice and the occurrence of a relapse. Background. Little is known about the prognosis of low back pain in general practice. Different designs and different results of preceding studies make drawing conclusions about the prognostic indicators, if any, of the course of low back pain in general practice difficult. Methods. For a period of 2 years, 15 general practitioners from Amsterdam and surrounding areas studied consecutive patients with chronic low back pain and those with a recent onset of low back pain. A large number of potential prognostic indicators were assessed at the initial visit. After the initial visit, each patient was monitored for a period of 12 months. The follow-up assessment was conducted with four weekly postal questionnaires. The associations among the potential prognostic indicators, the duration of the index episode, and the occurrence of a relapse were analyzed using multivariate Cox regression and logistic regression analysis, respectively. Results. Of the 605 patients identified, 443 were included in the follow-up period of assessment; the questionnaires were completed by 269 patients. In general, patients with less severe low back pain participated less often or did not complete the follow- up study. Thirty-five percent of the population still experienced low back pain after 12 weeks, and 10% still experienced it after 1 year. Approximately three of every four patients whose index episode ended before the end of the follow-up period had one or more relapse within a year. The analysis resulted in a model with four variables predicting the duration of the low back pain, including 'the duration of the low back pain preceding the initial visit,' 'receiving physical therapy,' 'pain intensity,' and 'history of back surgery.' Daily functioning appeared to be the only variable that was significantly associated with the occurrence of a relapse. Conclusions. Only a few variables appear to be related to the clinical course of low back pain seen in general practice. In particular, the duration preceding the initial visit and unexpectedly, receiving physical therapy were both associated with a longer duration of low back pain.