Fifty drunken drivers and 50 drivers with high blood drug concentrations arrested during the first four months of 1983 were selected for a study of rearrests for driving under influence of alcohol or drugs. Of the drugged drivers selected, 32 had been driving with high blood concentrations of diazepam (greater than 1.0 microM). 50% of these drivers were rearrested during the subsequent three years. The rearrest rate was low (6%) among those who had been driving with high blood concentrations of amphetamine (greater than 2.0 microM) or THC (greater than 0.010 microM). Among the drunken drivers arrested (BAC greater than 0.05%), the rearrest rate was 20%. The drivers were mostly rearrested for driving under the influence of alcohol.