Quality of life (QoL) is a significant parameter in estimating the social and interpersonal impact of psychopathology, clinical course, and response to treatment in many mental illnesses, particularly schizophrenia. The clinician's assessment and patient's subjective report are essential ingredients of this process. We describe the development and structure of a QoL questionnaire based on the patient's subjective understanding of the problems. Ninety areas identified by four groups of experts resulted in a 126-item questionnaire administered to 279 patients with a DSM-IV diagnosis of schizophrenia. A factorial approach led to 59 total items and two final scales (favorable and unfavorable), with three factors each. The Seville QoL Questionnaire (SQLQ) results can be presented as individual scores for each scale, or a total for both. Its psychometric properties have proven quite acceptable in reliability and validity, comparing favorably with other scales. SQLQ may prove to be a useful addition to QoL-measuring instruments.