Autism is a developmental disability that provides special challenges to families, schools, and adult support systems. An additional area that is affected by the symptoms of autism is medicine. The deficits associated with autism in the areas of communication and social skills, as well as the prevalence of challenging behavior can interfere with the diagnosis of illnesses and in some cases result in the provision of erroneous treatment. In this article, the authors present two case studies describing individuals with autism whose catastrophic illnesses were misdiagnosed due, at least partially, to their autism. Obstacles to medical diagnosis and treatment are discussed, and recommendations for future research are provided.