Patients who are admitted to psychiatric inpatient wards often undergo a medical screening examination in the emergency department to rule out serious or underlying medical conditions that may be better treated elsewhere. Unfortunately, prior research has been conflicting on the relative merits of various screening procedures, making it difficult to implement guidelines. A systematic review of the literature was undertaken to research the current state of knowledge in medical screening procedures. Electronic searches were conducted in PubMed, MEDLINE, and the Cochrane Library for publication years 1966-2003. No restrictions were placed on language or on quality of publications. Twelve studies were found that reported specific yields of various screening procedures. Results indicate that medical history, physical examination, review of systems, and tests for orientation have relatively high yields for detecting active medical problems in patients presenting with psychiatric complaints. Routine laboratory investigations generally have a low yield for clinically significant findings. However, these should be added selectively for four groups at higher risk of serious medical conditions, i.e., the elderly, substance users, patients with no prior psychiatric history, and patients with preexisting medical disorders and/or concurrent medical complaints.