Computer-based analyses of the EEG-records were performed in 18 hyperkinetic children. Thirteen of these patients displayed a positive response to clinical treatment with methylphenidate. Discriminant analyses of native EEG-records and differences between the spectrums from the EEG with and without medication made it possible to properly classify 73.3 or 80%, respectively, of all patients. Even based on a relatively small sample it is possible to make predictions as to the effectivity of stimulant treatment solely on the basis of EEG-findings.