The impact and quality of select pharmacists' interventions were assessed by four physicians with pharmacology experience. Each physician was sent 30 interventions and asked to indicate if the intervention by the pharmacist was of a positive nature and would prevent morbidity and/or mortality. They were also questioned regarding effect of the intervention on hospital stay. Each physician received 15 interventions which were, and 15 interventions which were not assessed by three other physicians. Of the 15 interventions assessed by all four physicians there was favourable agreement among the physicians with respect to the impact of the intervention with 86.7 percent (52 of 60) of the judgements indicating that the pharmacists' intervention had a positive effect on therapy. There was less agreement with regard to whether hospital stay would, and the extent to which it would, have been prolonged. Using consensus it was estimated that eight of 15 interventions would have prolonged stays approximately 3.7 days each. The use of physicians was helpful in assessing the impact of pharmacists' interventions.