Analysis of relative value units (RVUs) was used to quantify patient-care productivity of radiologists in 19 multispecialty group practices and to determine how productivity is affected by certain characteristics of the practices. The RVUs used in this study are the professional component RVUs developed by the American College of Radiology and the Health Care Financing Administration and published as the Radiology Relative Value Scale. An RVU workload was calculated by multiplying the number of times each procedure was performed by the procedure's corresponding RVU; the sum of these products gave the overall professional RVU workload. Five productivity indexes were calculated. The physician index denotes the ratio of the total number of physicians in the clinics to the total number of radiologists. The availability index denotes the fraction of radiologists who are available to perform clinical work after deductions are made for time away from clinical work. The difficulty index measures, in RVUs per examination, the level of complexity of the overall examination mix. The examination index measures examinations per available radiologist, and the RVU index measures RVUs per available radiologist. Altogether, the 19 clinics reported 3,234,451 examinations performed by 299 radiologists. The computed overall indexes were as follows: physician index = 20 physicians per radiologist; availability index = 0.77; difficulty index = 2.27 RVUs per examination; examination index = 14,098 examinations per year per available radiologist; RVU index = 32,065 RVUs per year per available radiologist. When the clinics were grouped according to characteristics of the practices, the RVU index was higher for single-site practices, high-prepaid practices, outpatient-only practices, and practices without radiology training programs. Fifty-two percent of the RVUs were in general radiology, 37% in sectional imaging, and 10% in special procedures. The concept of RVU workload is timely because it undoubtedly will be used to compare workloads across medical subspecialties, and these workloads are likely to be related by third-party payers to compensation.