Data on drug assignment from patients' case records were used to: 1) derive a computer formula for assignment to one of three major drug categories, 2) compare the results from this formula with those from a previous formula using prototype data, and 3) determine the agreement between this formula's results and the drug assignments made by the patients' physicians. The authors conclude that the computer can regularly suggest assignment to one of three major drug categories, although the clinician will still have to make the final decision.Abstract Teaser