This chapter examines the idea that the low prevalence of rare diseases poses specific problems to the patients. For this purpose, the chapter investigates to what extent interviewees with a rare disease thought rarity leads to specific problems, to what extent these interviewees believed the difficulties they encountered related to other dimensions of their disease, and to what extent they believed rarity had consequences on other dimensions of their life than healthcare-related issues. It is not so much the rarity of the disease that comes to the fore, but rather the difficulty caregivers have in meeting patients’ expectations for care. Rarity raises however many questions regarding the relationships with others, and, when the disease has a strong influence on daily life, it often creates a need to meet with other patients with the same disease.