In response to recent changes in hospital financing and in residency training requirements, teaching hospitals are implementing models of care that do not use housestaff. However, the relative cost and quality of such models remains poorly studied. We conducted a randomized controlled trial to compare a nurse practitioner (NP) service to a traditional housestaff (HS) service for general medical patients in a major teaching hospital. Study data were collected from hospital records and patient interviews at admission (ADM), discharge (D/C), and 6 weeks after discharge. At admission, NP (n=137) and HS patients (n=182) were similar (P> 0.1) in mean age (47 vs. 48 years), gender (38% vs. 40% male), race (36% vs. 37% white), comorbidity (mean Charlson scores, 1,2 vs. 1.5), severity (1-10) of patients' most bothersome symptom (mean scores, 9,0 vs. 8.8) and functional status (32% vs. 36% dependent in > 1 ADLs; 64% vs. 61% dependent in > 1 lADLs). In an intention-to-treat analysis, primary study outcomes were similar (P> 0.1 ) in the two groups: Nurse Practitioner : Housestaff Mean decrease in V of dependent ADLs (ADM to D/C) 0.2±1.0 0.2±0.8 Mean'decrease inl'of'c IADLs (ADM to D/C) 1.0 ± 2.3 1.2 ± 2.3 Mean improvement in symptom severity scores [ 5.3 ±3.5 ; 5.0 ±3-0 ccurrence of > 1 hospital-acquired complications : 5% ; 9% Mean # of consyl'tationstp other'services.9 + I.[ 1.8+ Ü Secondary outcomes in NP and HS patients were also similar (P> 0.1): in-hospital mortality (0.7% vs. 0.6%), 6-week mortality (2.2% vs. 2.2%), mean length of stay (5.3 vs. 5.0 days), mean total hospital charges ($9817 vs. $9452), and mean patient satisfaction (0-100) scores (84 vs. 81)- Results were similar when analyses were limited to patients receiving care on the randomly assigned service. In summary, in a randomized trial of general medical inpatients, several outcomes reflecting quality and efficiency of care were similar in NP and HS services. If generalizable to other teaching hospitals, the results suggest that a NP-based model of care may be a viable alternative to traditional HS care.