The practical value or usefulness of any investigation is dependent upon the clinical information provided and subsequent interpretation; this is particularly important in the investigation and classification of the epilepsies. For two months the histories from clinicians and EEG technicians were prospectively evaluated from 255 consecutive patients. The histories were interpreted by a single paediatric neurologist who was blinded to their origin. The histories were reported as "adequate' or "inadequate', and "diagnostic' or "non-diagnostic' (of epilepsy). Overall 92% and 40% of technicians' and 41% and 13% of clinicians' histories were considered to have been "adequate' and "diagnostic', respectively. These results have implications for the electro-clinical interpretation of the EEG.