Objective: Although longitudinal care constitutes the bulk of primary care, physicians receive little guidance on the fundamental question of how to time follow-up visits. We sought to identify important predictors of the revisit interval and to describe the variability in how physicians set these intervals when caring for patients with common medical conditions., Design: Cross-sectional survey of physicians performed at the end of office visits for consecutive patients with hypertension, angina, diabetes, or musculoskeletal pain., Participants/setting: One hundred sixty-four patients under the care of 11 primary care physicians in the Dartmouth Primary Care Cooperative Research Network., Measurements: The main outcome measures were the variability in mean revisit intervals across physicians and the proportion of explained variance by potential determinants of revisit intervals. We assessed the relation between the revisit interval (dependent variable) and three groups of independent variables, patient characteristics (e.g., age, physician perception of patient health), identification of individual physician, and physician characterization of the visit (e. g., routine visit, visit requiring a change in management, or visit occurring on a "hectic" day), using multiple regression that accounted for the natural grouping of patients within physician., Main Results: Revisit intervals ranged from 1 week to over 1 year. The most common intervals were 12 and 16 weeks. Physicians' perception of fair-poor health status and visits involving a change in management were most strongly related to shorter revisit intervals. In multivariate analyses, patient characteristics explained about 18% of the variance in revisit intervals, and adding identification of the individual provider doubled the explained variance to about 40%. Physician characterization of the visit increased explained variance to 57%. The average revisit interval adjusted for patient characteristics for each of the 11 physicians varied from 4 to 20 weeks. Although all physicians lengthened revisit intervals for routine visits and shortened them when changing management, the relative ranking of mean revisit intervals for each physician changed little for different visit characterizations-some physicians were consistently long and others were consistently short., Conclusion: Physicians vary widely in their recommendations for office revisits. Patient factors accounted for only a small part of this variation. Although physicians responded to visits in predictable ways, each physician appeared to have a unique set point for the length of the revisits interval.