The present study assessed drug use and the validity of self-reports of drug use among young people seeking treatment. On admission the participants (n = 316), 215 males and 101 females, were interviewed about their drug use. Urine samples were collected to screen for alcohol, amphetamine, benzodiazepines, cannabis, cocaine, methylenedioxymethamphetamine (MDMA) and opiate use. Self-reports of substance use were compared with urinalysis results. Seventy-three percent of the participants reported use of two or more substances. Single substance users were primarily alcohol users. Kappa agreement between self-report and urinalysis results was of acceptable concordance (> or = 0.65) except for alcohol (kappa = 0.19). Conditional kappa values were good (> or = 0.85) with exception of opiates (cond. kappa = 0.57). The self-reports were generally reliable among young people seeking treatment. No significant differences (p > or = 0.54) were found in the validity of self-reports between the genders.