Purpose: To investigate relevant adults' perceptions of behavioral problems in 66 children with newly diagnosed "epilepsy only" and in 63 healthy gender-matched classmates. Methods: Parents' and teachers' perceptions of the children's behavioral problems were quantified by using the Total Problem score of the Child Behavior Checklist (CBCL) and the Teacher's Report Form (TRF), after correction for epilepsy-related item ambiguity. Questionnaires were filled out immediately after diagnosis and 3 and 12 months later. Relations with demographic and educational variables, school attitudes, and interview -derived prior adversities were analyzed. Results: As a group, children with cryptogenic rather than those with idiopathic epilepsy have more behavioral problems than do healthy classmates. Family troubles and long-standing behavioral and learning problems are associated with more behavioral problems. The child's adaptation to the adversity of epilepsy onset is important. No adverse effect of antiepileptic drug (AED) treatment was found. Although the percentages of patients with clinically relevant (mean of controls + 2 SD) behavioral problems are consistently 25% (parents) and 22% (teachers), at each assessment, different children contribute to these percentages. In not a single child did parents and teachers agree on the presence of clinically relevant behavioral problems. Conclusions: (a) Behavioral problems are common in "epilepsy only," but are not persistent. (b) Agreement between parent's and teacher's perceptions of behavior is low. (c) Behavioral problems are perceived to occur already in the earliest stage of the disease.