The clinical, individual and family background characteristics of the first 100 admissions to a secure psychiatric unit for adolescents are described. A third of adolescents constituted a risk to themselves and two-thirds had committed a recent serious offence. Mixed patterns of major offending were present. The family and personal histories revealed high levels of disruption and disadvantage. Sexual offenders had significantly more involvement from special education, residential care and child psychiatry prior to referral. Adolescents with psychotic disorders were less delinquent than the other admissions; however, the majority presented as a risk to themselves and over a third had been involved in serious offending. The major single predictors of continued need for secure provision after discharge from the unit were recent major offending, being a risk to others at the time of admission and being admitted from a secure setting. The need for appropriate after-care provision for severely disturbed adolescents is emphasized.