This paper focuses on the importance of data collected not only from controlled clinical trials, but also from naturalistic treatment experience. In particular we examine the use of divalproex sodium either as monotherapy or as part of combined therapy on an in-patient ward for adolescents aged 13-18 years. All admissions in which divalproex sodium use was attempted (n=36) were analysed over a 1-year period. The most common use was in patients with a mixed-presentation bipolar disorder (n=16), followed by patients with major depression (n=7), mania (n=4) or psychoses not otherwise specified (n=4). Divalproex sodium use was evaluated in the control of mania, psychosis, agitation, mood swings, aggression and/or anxiety. Overall, the use of divalproex sodium was associated with a marked improvement along all psychopathological variables in the vast majority of patients. Few side-effects or medical complications were noted. We believe that divalproex sodium is a potentially useful drug in adolescent patients with varying forms of psychopathology.