Taiwan's Rare Disorders Control and Orphan Drugs Act defines them as "disorders determined by the [Rare Disorders and Orphan Drugs Appraisal] Committee to be of an incidence below a level defined and announced by the competent central authority."
台灣「罕見疾病防治及藥物法」中明文規定：「罕見疾病係指疾病盛行率在中央主管機關訂定之公告標準以下、經委員會認定者」。