Objective: To describe the testing requirements and practices of emergency physicians (EPs) when conducting a medical screening examination of psychiatric patients. Methods: An anonymous survey was developed and mailed to 500 EPs randomly selected through American College of Emergency Physicians membership rolls. Results: Two hundred ninety surveys were returned (58%). Eighty-five percent of the respondents were male, 70% practiced in a community setting and 28% in an academic setting, 58% were emergency medicine (EM) residency-trained, and 88% were EM board-certified or board-eligible. Ninety-eight percent stated they were actively involved with the psychiatric medical screening exam (PMSE). Routine testing was required by 35% of the respondents, with 16% being required by ED protocol, and 84% by the psychiatrist/psychiatric institute. Of those with required testing, tests required were: complete blood cell count (56%), electrolytes (56%), serum alcohol (85%), serum toxicology screen (31%), urine toxicology screen (86%), electrocardiogram (18%), liver function test (16%), blood urea nitrogen (45%), and creatinine (40%). Many clinicians believed that certain tests were unnecessary as part of a PMSE. There was no statistical difference between the opinions of the physicians required to test and those not required to test in terms of which tests they thought were a necessary part of a PMSE regardless of the patient's clinical presentation. The EM-trained physicians were also found to be significantly less likely to think certain tests were necessary for the PMSE when compared with the non-EM-trained physicians. Conclusions: Routine testing was required as part of the medical screening examination of psychiatric patients for only one-third of the respondents. Few respondents believed that any of these tests were necessary. Emergency medicine-trained physicians were less likely to feel that routine testing was necessary.