Of suspects arrested for suspected driving under the influence, 201 were judged by 25 DRE's as being impaired by drugs other than alcohol. Analysis of blood samples for 173 of these suspects identified 13 psychoactive substances and over 40 drug combinations. When DRE's judged a drug other than alcohol to be present, they were correct 94 percent of the time. It was rare for DRE's to claim drug use and for no drug to be found in blood. DRE's were able to identify correctly at least one drug other than alcohol in 87 percent of suspects and to identify correctly the specific drug in 79 percent. Only six suspects (3.7 percent) who had used drugs had blood alcohol contents over .10 percent, suggesting that most, if not all, would have been released if symptoms of drug use had not been recognized. 2 references and 1 note.