Musicians are at increased risk for mental disorders, in particular performance anxiety, likely due to high levels of occupational stress, and special personality traits and coping skills. In this cross-sectional study, we examined the accuracy of the MINI-plus to diagnose performance anxiety as social phobia. Routine Outcome Monitoring data were used to compare clinical and psychosocial characteristics of the first 50 musicians (39.1 years ± 12.5 yr, 42% male) visiting our outpatient clinic for performing artists to large samples of psychiatric outpatients and subjects from the general population. We found that 82% (n = 41) of the music outpatients met the criteria of an Axis I psychiatric disorder. Performance anxiety was diagnosed in 30% (N = 15), often inaccurately classified as social phobia with the MINI-plus. Musicians displayed significant less functional limitations but more narcissism in comparison with general outpatients (p = 0.001). Diagnostic challenges of musicians seeking psychiatric care are thoroughly discussed.