This study argues that narratives of contested illnesses amplify the credibility dilemma (Halkowski 2006) that all patients face in their doctors' offices: we are socially expected to tell out-of-the-ordinary stories within the 'ordinary cast of mind' (Sacks 1984, 1995). Patients/narrators with contested illnesses are particularly challenged by the narrative demands of the reportability paradox: as more eventful a story sounds the more reportable, but the less credible it will be. It is speculated that in personal interactions, narratives of contested illnesses are likely to become contested narratives by virtue of the vague, subjective, and out-of-the ordinary nature of their realities that seems to push further the conventional boundaries of what we can afford to accept as rational and medically possible. The hesitancy in believing these patients' accounts may be explained by the oscillation between the belief in the existence of certain symptoms that have a conventional reference to the actual, experiential world (e.g., headaches) and the disbelief in the patients' emplotment of those symptoms reporting unconventional syndromes, as that emplotment challenges conventional diagnosis. Memoirists' strategies to construct credibility are summarized in three main narrative strategies: (1) constructing credibility by challenging reliability, that is, by drawing on discursive devices of ambiguity and contradictions; (2) constructing credibility by means of "reported evidentials" that assert the narrator's visceral knowledge as complementary to the knowledge of medical science; and (3) constructing credibility by displaying figurative linguistic devices as ontologically valid conceptual tools to represent experience. Writing memoirs plays a legitimization function in asserting patients' conditions as existentially real, transforming contested narratives into ontological narratives.