Patients with acute, complex behavioral syndromes combined with impaired comprehension and communication are difficult diagnostic challenges. Using a structured mental status interview can significantly reduce the chance of overlooking the presence of cognitive dysfunction. The authors tested the applicability of the cognitive portion of the Alzheimer's Disease Assessment Scale (ADAS-COG) as a screening instrument on a psychiatric consultation service. The ADAS-COG compared favorably with the Mini-Mental State Exam (MMSE), but appeared to be less influenced by educational level. The advantages and disadvantages of using each of these tests on a psychiatric consultation service are discussed.