Associations between psychopathology and gender, duration of MS, disability and therapy with beta-interferons were studied in multiple sclerosis (MS) outpatients. A controlled descriptive epidemiological study was carried out in two Italian outpatient MS centres on 50 outpatients with clinically definite relapsing–remitting MS presenting for regular follow-up and 50 healthy controls matched for sex, age and educational level. Subjects were assessed with the Structured Clinical Interview for DSM-IV (SCID I), the Beck Depression Inventory (BDI) and the State Trait Anxiety Inventory (STAI). MS patients reported a higher prevalence of psychiatric disorders (odds ratio 3.17), with 46% (n=23) suffering from major depressive disorder. The risk of suffering from any non-mood psychiatric disorder was also higher in MS patients than in controls (odds ratio 2.67). Risk factors for depression were female sex and severity of disability, but not therapy with interferon beta or longer duration of illness. Disability level, but not therapy with beta-interferons, is a risk factor for depression in MS outpatients. Regular screening for depression in this population is appropriate.