This study evaluates the impact of the Renal Stone Center (RSC) at Yale University School of Medicine on the extent of the diagnostic search for urolithiasis risk factors at the Yale-New Haven Medical Center and four affiliated community hospitals. Using a multiple time series design and a Physician Performance Index (PPI) based on multiple normative practice criteria, the hospital and outpatient charts of 1,924 patients with a primary diagnosis of urolithiasis at the five hospitals were examined to determine whether there was a change over time that could be related to the RSC. There was no statistically significant improvement in the PPI at four of the five hospitals. At the fifth, there was a statistically significant improvement that possibly was related to factors other than the RSC. Routine blood, urine, and X-ray tests usually were performed well. However, the history of urolithiasis risk factors and the examination of 24-hour urines were generally done poorly or not at all, and this generalization held true (although modified somewhat) even when physician office records were examined as well.