Aim To examine whether an internal medicine interdisciplinary floor team enhances the hospital and clinical outcomes for seniors with acute medical illness. Methods Seniors admitted to medical floor teaching services of a USA teaching hospital were recruited and allocated to the interdisciplinary (ITD; n = 236) and usual care teams (n = 248). Compared with the usual care team, the interdisciplinary team physicians carried out daily “geriatric” assessment and management, and led the interdisciplinary team meeting designed for improving interprofessional collaboration. Results After controlling for patient and physician characteristics, the mean hospital length of stay in the ITD team (6.1 days; 95% CI 5.2–7.7 days) was 0.7 days shorter than that in the usual care team (6.8 days; 95% CI 5.7–8.3 days; P = 0.008). There was no significant difference in delirium and 30‐day hospital readmission between care groups. Conclusions Notwithstanding partly positive associations, the results from the present study suggest that interdisciplinary team‐based care is, at best, associated with enhancing the clinical and hospital outcomes for seniors with acute medical illness. Geriatr Gerontol Int 2013; ●●: ●●–●●.