EPs frequently transfer psychiatric patients to psychiatric hospitals with the approval and acceptance of a psychiatrist. EPs and psychiatrists have an unknown set of testing routines and requirements that are used to determine medical clearance of the psychiatric patient. The purpose of this study was to compare the routine and required testing performed by EPs as compared with psychiatrists. A survey of routine and required test ordering for the medical clearance of patients presenting with psychiatric complaints by EPs and psychiatrists was developed. The survey contained information on the physician and hospital demographics, tests routinely performed, required tests, and estimated cost of testing. The survey was distributed to all of the 1,055 EPs in Illinois using the American College of Emergency Physicians database and all of the 117 psychiatrists at state-operated psychiatric facilities in the state of Illinois. The surveys were mailed and remailed to the nonresponders in both groups. The results were inputted into an SPSS (Chicago, IL) program to determine frequencies, descriptives, and correlations. The study results comparing the EPs with the psychiatrists were performed using Fisher exact testing. The survey was returned by 507 (48.1%) of the EPs and 65 (56.4%) of the psychiatrists. A total of 37.0% of EPs responded who were mostly 31 to 40 years old (187 of 506), male (347 of 469), and board-certified (348 of 477). The psychiatrists were mostly 51 to 60 years old (36 of 56), male (34 of 57), and board-certified (42 of 59). The most frequent routine and required tests ordered by EPs and psychiatrists were a urine drug screen (routine 378 of 507, 45 of 66 and required 381 of 507, 31 of 66), alcohol (348 of 507, 33 of 66 and 348 of 507, 33 of 66), and complete blood count (270 of 507, 53 of 66 and 334 of 507, 34 of 66) and least frequently electroencephalogram (0 of 507, 2 of 66 and 1 of 507, 0 of 66), computed tomography scan (6 of 507, 3 of 66 and 2 of 507, 0 of 66), and lumbar puncture (1 of 507, 2 of 66 and 0 of 507, 0 of 66) respectively, at a most frequent estimated cost of required testing of $101 to $200 for EPs (102 of 507) and $201 to $300 for psychiatrists (13 of 66). There were 10 of 16 differences in routine test ordering and three of 16 required tests performed by EPs compared with psychiatrists. Although the number of sets required by both groups were different, the tests required by psychiatrists and EPs for medical clearance of the psychiatric patients were found to be similar. It is unknown if the psychiatrists influenced the ordering behavior of the EPs. However, this study does demonstrate a difference in the routine test ordering, implying that these is a difference in the approach to the patient in the ED. Further means to obtain congruence in the testing protocol of psychiatric patients would be a valuable endeavor.