Galen conceives of wounds, fractures, and similar conditions as belonging to one of the highest genera in his taxonomy of disease. This classification is puzzling, as much from an ancient Greco-Roman perspective as from a contemporary one. In what sense are wounds and other injuries diseases? The classification appears more perplexing in light of Galen's method of conceptual analysis, which takes ordinary language use as a starting point. What, then, motivated Galen's departure from common Greek conceptions of disease? This article examines the class of disease that Galen called “dissolutions of continuity” in the broader context of his system of nosological definition and classification. It concludes that Galen's analysis of wounds is driven by his theory of causation, and by his localization of disease and its mechanism inside the body, a conceptualization typical of Greco-Roman medical writing. This conclusion sheds further light on Galen's method of disease classification and the role of dissolutions within it.