A self-rating version of the UKU Side Effect Rating Scale has been developed. The present study examines the agreement between patients' self-assessment of side effects and the attending clinicians' ratings. The patient sample consisted of 63 patients with schizophrenia under maintenance treatment with risperidone, clozapine or classical antipsychotics. Approximately two thirds of the patients used concomitant medication with e.g. benzodiazepines, SSRIs, anticholinergics. Most inter-correlations between scores for single, corresponding items, subscores of Psychic, Neurological, Autonomic and Other side effects, as well as the Total Score from the patient version of the UKU Side Effect Self Rating Scale (UKU-SERS-Pat) and the clinician version (UKU-SERS-Clin) were found to be statistically significant. Patients reported side effects more frequently and or rated symptoms more severe than the clinicians. The results support the validity of the SERS-Pat and suggest that patient rated side effects may provide important clinical information not detected by clinician rated interviews. Such information can be utilised both in clinical investigations, in development of treatment programs and for individual patients in clinical practice.