Hospital discharge register information was collected on length of stay (LOS) of all those children and adolescents less than 18 years old in psychiatric inpatient treatment in 1990 (n=818) and 1993 (n=958) in Finland. The predictors for LOS > 60 days included previous psychiatric inpatient treatment, involuntary treatment, and treatment in adolescent psychiatric unit. No psychiatric diagnosis was associated with shorter LOS. Girls and the under-school-age group had significantly shorter LOS. There were only rather minor differences in LOS between different diagnostic groups.