Comorbidity with other psychological problems (PP) complicates the course of attention deficit-hyperactivity disorder (ADHD) and makes treatment more difficult. The purpose of the present study was to (a) study the correspondence between the perceptions of parents and teachers about PP, (b) determine which PP predict the severity of the manifestations of ADHD, and (c) analyze the role of age and learning disabilities (LD) in the development of PP and ADHD. The participants were 72 children with a clinical diagnosis of ADHD. The PP were measured using rating scales filled out by parents and teachers. The results showed high correspondence between the two informant groups in rating the problems of behavior and overactivity. However, agreement on emotional symptoms was much lower. Inattention, emotional lability, and conduct problems predicted the severity of the ADHD. Finally, the younger children with ADHD+LD experienced more associated problems than the older children. (Contains 5 tables.)