A total of 2500 individuals, aged 14-70 years and living in Castille and Leon (Spain), were surveyed in the spring of 1989 with regard to their drug consumption and patterns of use. 'Lifetime' drug users' rates were 30.0% for cannabis, 5.4% for cocaine, 5.2% for amphetamines, 2.4% for psychedelic drugs, 1.5% for opiates, 1.1% for tranquillizers, and 0.4% for inhalants. 'Regular' drug users were more common among cannabis--2.8% of the surveyed--and less frequent among cocaine, opiates and amphetamine users--0.3% of everyone of the substances mentioned above. 'Lifetime' drug users were more common among males than among females, among singles than among married, in those younger (18-29 years of age) and with work problems. The starting age of drug consumption ranged between the average of 15.6 years of age for those who consumed inhalants and 19.5 for those who consumed cocaine. The results allow a better understanding of the pattern of drug use in Castille and Leon (Spain), as well as the 'high' prevalence of drug use in our region.