The objective of this review is to establish whether the medical literature validates a causal relationship between upper extremity disorders and work activities. Selected articles were reviewed using a Diagnostic Medical Criteria. Articles meeting this criteria were further reviewed for validity. Only 14 of 52 reviewed articles were felt to encompass medical criteria. However, these articles also contained what appear to be major validity flaws. Very little of the written material dealing with the issue of work-related upper extremity conditions incorporates what are felt to be sound medical diagnostic criteria in the definition and identification of these conditions. None of the reviewed studies have established a causal relationship between distinct medical entities and work activities. Further research using well constructed studies that incorporate reliable epidemiologic and accepted diagnostic criteria is needed. In this manner, the best of the medical and epidemiologic fields can be applied to solving these problems.