To investigate the prevalence of analgesics containing dextropropoxyphene (DXP) or codeine in individuals suspected of driving under the influence of drugs, we analysed all blood samples in which drugs were screened for in cases of suspected drunken driving in Sweden during the years 1992-1997. DXP was found in 130 (2.7%) and codeine in 388 (7.9%) of the 4896 drug-screened cases. The ratio between the number of DXP and of codeine cases and prescription of defined daily dose/1000 inhabitants during a 12-month period (DDD) was determined. The quotient for DXP was trebled from 1992 (0.99) to 1997 (2.89), while the codeine quotient decreased by 9% (from 6 to 5.5). The blood samples showed polydrug use in all but 28 cases of the 486 cases where DXP and/or codeine was found. In 71% of the 486 cases benzodiazepines were also present and in 38% of the cases amphetamine and/or cannabis were present. It was concluded that analgesics containing DXP or codeine are not drugs of primary interest in this specific population. Nevertheless, because of the high toxicity of DXP, especially when combined with alcohol or other drugs, the increase in the DXP prevalence gives reason for concern, since the studied population represents a group of individuals who use large doses of therapeutic or illegal drugs.