This study was performed on a representative sample of the Danish population in order to investigate the connection to the use of psychoactive drugs and quality of life (QOL) by way of a questionnaire-based survey. The questionnaire was mailed in February 1993 to 2,460 persons aged between 18 and 88, randomly selected from the CPR (Danish Central Register), and 7,222 persons from the Copenhagen Perinatal Birth Cohort 1959-61. A total of 1,501 persons between the ages 18 and 88 years and 4,626 persons between the ages 31 and 33 years returned the questionnaire (response rates of 61.0% and 64.1%, respectively). Variables investigated in this study were ten different psychotropic drugs and quality of life. Our study showed that over half the Danish population had used illegal psychotropic drugs. The most commonly used was cannabis (marijuana) though experience of this drug appeared not to co-vary with QOL to any significant extent. Cocaine, amphetamine, and psilocybin had been used by 1.2 to 3.3% of the population and this varied with QOL to a clear albeit small extent. LSD has been used by 1.2% of the population and the users had a QOL score 10% lower than those who had never used psychotropic drugs. The group with the lowest quality of life was found to be persons who had used heroin, morphine, methadone, and a mixture of alcohol and tranquilizers (10-20% below the group with the highest quality of life).