Sixty proband children (P) of bipolar I parents and 60 control children of normal parents (C), in the age range 10-17, were investigated clinically by K-SADS-E interview and psychologically by personality inventories. In the global psychopathology rate of 63% in P children and 25% in C children, depressive disorders reached 8% in P children and 0% in C children, while depressive personality traits reached 22% in P children and 15% in C children. Cluster analysis evidenced a variety of personality structures, but 3 clusters were striking: a cluster characterized by high anxiety and depressive reactivity (17% P and 5% C children), a cluster characterized by high depressive reactivity and emotional instability (5% P children), and a hyperthymic cluster (5 % P children). Sixty-seven percent of P children and 36% of C children showed deviant personality traits (p<.01).