Occupational caused lung disease (OLD) is almost always compensable, either by application to workers' compensation agencies or by a civil lawsuit. For this reason the diagnosis usually comes under close scrutiny. Several pitfalls can occur when a physician diagnoses a patient as having lung disease of occupational origin, especially when compensation is at issue. These pitfalls can trap both the attorney advocate and his client, and lead to a result opposite of that intended (e.g., the claim one supports can be denied). For purposes of discussion I have categorized the pitfalls as follows: A. Making an unsupported medical diagnosis (looking for a "quick fix"). B. Echoing an unsupported diagnosis made by someone else. C. Inadequate clarification of 'impairment' and 'disability.' D. Ignoring or minimizing relevant medical history. E. Arguing against yourself. F. Ignoring the possibility of a rare or unusual diagnosis. G. Not obtaining or reviewing independent chest x-rays and reports. H. Attributing causation with certainty when it is unwarranted by the facts. I. Relying on a claimant's own smoking history. J. Misinterpreting pulmonary function and arterial blood gas tests. K. Missing the real cause of a patient's complaint. L. Diagnosing occupational lung disease without attempting to remove the patient from the cause. M. Confusion over basic terminology and pathophysiology in OLD. N. Using sloppy or incorrect language, including misspelling. O. Not saying "I don't know," when you don't know. Pitfalls in diagnosis generally arise from either physician bias or inadequate evaluation. Although most pitfalls seem to be made by physicians on the plaintiff's side, they are also made by physicians on the defendant's side, as when bias interferes with recognizing a condition that is occupational in origin. Ideally, the fact that diagnosis of OLD involves the legal profession should not affect a physician's objectivity or clinical approach. Physicians have an obligation to help assure that deserving patients receive compensation, and that claimants without a compensable occupational illness are not unjustly rewarded. However, the attorney's need to prove a diagnosis "with medical certainty," and the defendant's need to refute that diagnosis with equal certainty, often skew what would otherwise be a straightforward diagnostic process. Resulting pitfalls in diagnosis can, in the end, trap the physician advocate and the side he is trying to help.