To review the impact of case management programs on health care resource use; their impact on patient satisfaction, quality of life, and functional status (patient-centered outcomes); and their cost-effectiveness, we reviewed the English language literature utilizing the following MEDLINE and HealthSTAR headings: case management, patient care planning, patient-centered care, disease management, care management, and managed care programs. Bibliographies of relevant articles were also reviewed. Only randomized controlled trials were included. Data were extracted manually from relevant publications and are presented descriptively because formal, quantitative methods were not applicable. Nine studies met our inclusion criteria. Of the seven studies examining case management's impact on health resource use, only two found a positive effect. Both successful programs targeted patients with specified disease conditions and care was supervised by a medical subspecialist. None of the programs targeting general disease conditions or supervised by generalists reported a positive effect. All six studies examining patient-centered outcomes reported a positive impact. These effects were unrelated to the patient's conditions or the study personnel. Both studies examining clinical parameters found a positive impact. Only three studies examined costs; all reported nonsignificant cost savings. While case management programs offer theoretical benefits, few examples of successful programs were found. Positive effect was related to disease condition and specialty training of study personnel. Patient-centered outcomes were often improved upon but at unknown cost. Further multisite clinical trials are needed to define case management's role in our future health care system.