BACKGROUND: Patient outcomes with hospitalist care have been studied in many settings, yet little is known about how hospitalist care interacts with trainee care to affect patient outcomes in teaching hospitals. OBJECTIVES: The aim of this study was to compare patient outcomes between hospitalist-preceptors and hospitalists working alone (isolating the effect of housestaff involvement), and between hospitalistpreceptors and academician-preceptors (isolating the effect of attending type, given housestaff involvement). CONCLUSIONS: Preceptor-led medicine services were associated with more readmissions within 30 days, shorter lengths of stay, and lower index admission-associated costs. However, when considering cumulative hospitalization costs, patients discharged by academicianpreceptors incurred the highest cost and hospitalistpreceptors incurred the lowest cost.KEY WORDS: quality of health care; hospitalists; academic medical centers; patient readmission; hospital costs; length of stay.