Simple screening questionnaires for major psychiatric disorders are needed for epidemiological research and clinical work. We describe the characteristics of the Hopkins Symptom Checklist-25 (HSCL-25) as a screening instrument in a two-phase epidemiological survey using the Structured Clinical Interview for DSM-III-R (SCID) as a diagnostic tool. The material consisted of 1609 subjects aged 31 years who were asked to participate in a health survey. The invitation included the HSCL-25 questionnaire. All "screen-positive" (HSCL-25 mean>/=1.55) subjects and every tenth "screen-negative" subject were invited to participate in the SCID interview. The sensitivity of the HSCL-25 for any present DSM-III-R axis-I psychiatric disorder was 48%. The specificity was 87%. The sensitivity of cases with comorbid psychiatric disorders was 100%. The HSCL-25 is a moderate instrument for screening with present axis-I DSM-III-R psychiatric disorders in a young adult population. It can be recommended for screening of psychiatric disorders.