The goal of impairment assessment is to accurately estimate the loss of structure and/or function due to an injury or illness. The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) sometimes provides two or more methods for rating a given condition, or, in the case of two or more impairing conditions, it may be inappropriate to rate less significant conditions if the rating for the primary impairment already takes into account the deficit(s). Either scenario offers opportunities for “double-dipping” or rating the same impairment more than once. Duplicative ratings commonly occur when two or more impairing conditions are present in a single organ system and even more often if multiple organ systems are involved. Because of methodological changes, ratings using the AMA Guides, Sixth Edition, are less susceptible to double-dipping than those from earlier editions, especially musculoskeletal ratings. To avoid duplication, the rater must look closely at all elements included in the impairment classes and determine if any similarity exists in the other organ systems or conditions rated (eg, is the patient's coronary artery disease responsible for the diminished exercise capacity, or is it the cardiomyopathy, or is it chronic obstructive pulmonary disease). When two or more conditions are present, evaluators should rate the higher or highest impairment and then eliminate, as much as possible, the influence of similar symptoms, signs, or diagnostic test abnormalities when rating the lower impairments.