191 DSM-III-R schizophrenic outpatients were interviewed about their experiences in selfregulation of medication by means of a structured questionnaire. 59% of the 178 patients giving relevant replies claimed to have varied their neuroleptic dosage; i. e. augmented, reduced or discontinued it without consulting their doctor. Modifiers reported more often that their relatives were in favour of the medication, but less often that they themselves thought it important for their health. Augmenters were older on average than non-modifiers. Patients' appraisals of their experience appeared to be realistic, so that psychiatrists could make use of them to co-determine treatment in the individual case.