The aim of the present study was to characterize sleep in conduct-disordered adolescents using polysomnography and spectral power analysis. The two hypotheses were that conduct disorder would be associated with objective sleep problems, and that conduct disorder--as a precursor of adult antisocial personality disorder--would be associated with the same kind of abnormal sleep architecture, with both increased deep sleep and delta power, as previously reported in antisocial personality disorder. The patients consisted of 15 adolescents (age range 13-17 years, mean age 14.7 years) with histories of antisocial behavior so functionally impairing that they were ordered by child welfare to undergo a psychosocial evaluation in a closed social services ward. The healthy age-matched controls comprised 20 volunteers recruited with a newspaper advertisement. Opposite to earlier subjective sleep studies among conduct-disordered children, no significant differences in sleep parameters were observed between the two groups. The adolescents with conduct disorder slept a little bit longer, but the percentage amount of different sleep stages did not differ significantly between the two groups. Relative spectral power of sleep, delta power in particular, was similar in both groups, assessed in total sleep time as well as in first half of it. Different alternative explanations for these findings are discussed.