The Clinical Case Study is one of the oldest medical discursive genres where a new medical or unusual illness-related event, symptomatology or treatment is reported. It is necessary to deepen the knowledge of the patterns of regularity that underlie the way this genre is rhetorically organized as it carries a high pedagogical value in vocational training and in determining the success of young medical professionals who start publishing (Uribarri, 2007; Serrano, 2010). As part of a wider project, this article describes the rhetorical organization of the Case Report, a unit that corresponds to one of the main macromoves that shape the Clinical Case Study genre (Burdiles, 2012). The purpose of this study is to determine, by means of Genre Analysis (Swales, 1990, 2004), the rhetorical organization of the macromove Case Report of a corpus of 969 texts from nine medical specialties (Corpus CCM-2009). According to the results, this macromove has a rhetorical organization made up of three moves and eight rhetorical steps. It was observed, on one hand, that this pattern appears fairly regularly in the nine medical specialties, which would prove the existence of a common system of rhetorical conventions expressed in genre writing. On the other hand, it was found that these conventions have some variations associated with the nature of the various medical specialties.