We examined whether a policy change transferring prescribing privileges for oral nutritional supplements to dietitians resulted in fewer inappropriate outpatient prescriptions. This was a pre/post study design using a retrospective review of physician and dietitian prescribing for ambulatory patients during two separate time periods: physician prescribing, October to December, 1994; dietitian prescribing, April to June, 1995. Inappropriate prescriptions during each period were defined as those given to patients with normal nutritional status or with a contraindication to a high-energy, electrolyte-containing solution. The study was conducted in outpatient clinics at a Veterans Affairs teaching hospital. We found that dietitians gave fewer prescriptions to outpatients who were not malnourished or to outpatients who had a contraindication to receiving a supplement (11% vs 34%; P = 0.002). In addition, dietitians more often completed relevant laboratory assessments (75% vs 43%; P = 0.001) and more frequently arranged follow-up dietetic evaluations (84% vs 30%, P < 0.001) for ambulatory patients receiving supplements. We conclude that transferring nutritional supplement prescribing privileges to dietitians led to fewer inappropriate outpatient prescriptions and to more comprehensive nutritional assessments, as measured by relevant laboratory use and dietetic follow-up. Physicians more frequently prescribed supplements to outpatients who were not malnourished or who had contraindications to receiving supplements. Our results suggest that physicians would benefit from assistance with and/or education concerning oral nutritional supplements.