• One thousand unselected outpatients who presented puzzling diagnostic features were examined by the Mount Sinai Hospital consultation service. Examining facilities encompassed all the specialties in medicine and included the most comprehensive laboratory support, e. g., determination of basal metabolic rate, electrocardiogram, Kahn test, blood cell count, sedimentation rate, chest fluoroscopy, and stool and urine analysis, with such further procedures as indicated by the original complaint or preliminary findings. After all organic factors could be eliminated, in 81.4% of these diagnostic problems the patients were found to have psychological factors as the basis for their complaints and illnesses. Only 16.6% of the 1,000 patients had organic illness as the sole etiological factor. Emotional illness can and should be a positive diagnosis, not one of exclusion.