The aim of the study was to investigate factors related to initiation and abandonment of illegal drugs. A follow-up study on 53 drug addicts originally hospitalized because of parenterally acquired hepatitis was performed using questionnaires. The majority stated that curiosity and peer pressure were the main reasons for starting drug use. Family conflicts, school and mental problems were each reported by about 40% of the subjects. Thirty-nine patients (74%) had abandoned addictive drugs during the approximately 25 years that had elapsed since the hospital stay. All of these thought that own efforts had been most important in this achievement. Other important factors were help and support from family and friends, establishing a family or experiencing acute hepatitis or an overdose.