The development of depression in ill and healthy adolescents is explored and the question of whether hospitalization is accompanied by improvement in depression among cancer and non-cancer patients is addressed. Two studies, one between and one within subjects, longitudinal design with repeated measurement over 4 months, were carried out. MANOVA and ANOVA analyses were used. The three groups of subjects were (1) patients with cancer (N=30; mean age=15.5 years); (2) patients with some other disease (N=30; mean age=15.8 years); and (3) normal subjects (N=30; baseline age=16 years). Mean hospitalization was 55 days. The Beck Depression Inventory was used to assess depression. The pretest revealed a significant difference among the three groups in depression. After 4 months results show (1) depression was positively correlated with hospitalization stays of patients, and (2) there is a significant relationship between patients' (both groups) and healthy adolescents' depression. This study underscores the importance of evaluating patients' hospitalization stay in comparison with normal adolescents. (EMK)