This paper was submitted in response to the clinical commentary entitled "Diagnoses Enhances, Not Impedes, Boundaries of Physical Therapy Practice" (JOSPT 13(5):218-219). We have read with interest and respect the clinical commentary by Behr et al (1) regarding boundaries of physical therapy practice. Their review of "Pathological Origins of Trunk and Neck Pain-Parts I (2), II (3), III (4)" reflects some philosophical similarities and differences regarding the physical therapist's role in the differential diagnosis process.We believe that physical therapists should include a medical screening component in their examinations. This screening is a necessary adjunct to history and physical examination components, which are designed to identify mechanical dysfunction(s) related to patients' symptoms and/or functional limitations. The Review of Systems Checklists (Tables 5-10, Part I) (2) present items designed to screen a body system (i.e. gastrointestinal system) for general pathology. The checklists are NOT designed for screening specific diseases-such as peptic ulcer, cholecystitis, pancreatic cancer, or hepatitis. "Yes" responses should prompt therapists to refer their patient to a physician. This is clearly stated in the forward (5) and the subsequent articles (2-4). J Orthop Sports Phys Ther 1991;14(6):241-242.