Adolescent cancer is uncommon and presents an exceptional stress for the young patient and their parents. The emotional needs of adolescents with cancer are a major factor in the recommendation for the establishment of adolescent cancer units in major cancer centres in the U.K. However, there have been no prospective, longitudinal studies assessing the psychological impact of a diagnosis of cancer on the adolescent patient and their family. In 1994 we began a longitudinal study of the emotional impact of the diagnosis of cancer in patients and their families presenting to an adolescent cancer unit and of the coping strategies they employ. This first report presents the results of the study at the time of diagnosis in 42 adolescents, 34 mothers and 27 fathers. The Beck Depression Inventory (BDI) was used to assess depression and anxiety levels were measured using Spielberger's State Trait Anxiety Inventory (STAI). Adolescents and their parents completed the questionnaires on first admission to the adolescent cancer unit. The median time since cancer diagnosis was approximately 3 weeks. To provide normative data for the U.K. adolescent population, control values were obtained from 173 pupils of the same age and background. The results showed that, contrary to expectation, adolescents with cancer were no more anxious or depressed than the control adolescent population. Nevertheless, a substantial minority of patients and controls had elevated anxiety or depression scores. Girls were significantly more anxious (P = 0.011) and depressed (P < 0.0001) than boys. Mothers were the most anxious family members and were significantly more anxious than fathers (P = 0.038). Parental anxiety scores, especially mothers, were much higher than reported norms. There was no significant difference between mothers' and fathers' depression scores. Although at the time of diagnosis adolescent cancer patients are not more anxious or depressed than their healthy peers, many adolescents without cancer are anxious or depressed. Staff on adolescent cancer units should therefore be aware of the frequency of emotional disturbance in this population. Mothers are the most anxious family members. Although the findings are relatively reassuring at the time of diagnosis, follow-up data from this cohort will show whether anxiety and depression change with treatment involving intensive chemotherapy, surgery and radiotherapy and will indicate the coping strategies which patients and their families adopt in dealing with both the disease and its treatment.