This study was conducted to evaluate the benefit of comprehensive "medical clearance" (history, physical examination, vital signs, laboratory, radiography) in patients presenting to the Emergency Department (ED) with isolated psychiatric complaints. All patients 16 years and older who presented with a psychiatric complaint and required a psychiatric evaluation before discharge from the ED were included in the study. Data, obtained in a 5-month consecutive, retrospective chart review, included patient age, sex, initial complaint, past medical and psychiatric history, initial vital sign measurement, physical examination findings, laboratory analysis (electrolytes, complete blood count, toxicology screen), chest X-ray study results, and final disposition. The number of patients who could have been referred to a psychiatric unit after a history, physical examination, and stable vital signs, without additional laboratory or radiographic studies, was determined. There were 212 patients who met the inclusion criteria, and all their charts were available for review. Eighty patients (38%) presented with isolated psychiatric complaints coupled with a documented past psychiatric history. All received a comprehensive "medical clearance" in the ED followed by a psychiatric consultation. None of the patients had positive screening laboratory or radiographic results. All were either dispositioned home or to the psychiatric ED. The remaining 132 patients (62%) presented to the ED with medically based chief complaints or past medical history requiring further evaluation in the ED before discharge. The initial complaints of these patients correlated directly with the need for laboratory and radiographic "medical clearance" in the ED. Patients with a primary psychiatric complaint coupled with a documented past psychiatric history, negative physical findings, and stable vital signs who deny current medical problems may be referred to psychiatric services without the use of ancillary testing in the ED.