The Formosan serow (Capricornis swinhoei) is endemic to Taiwan. The wild population has declined dramatically over the past few decades and the species is listed as a “precious and rare species” protected under law in Taiwan. Disease investigations have been rare except for sporadic observations of wild individuals, and no long-term disease survey has been performed on this species. The objective of this study was to identify and report on the most common diseases in captive Formosan serows and determine the potential causes. Medical records of Formosan serows (n = 62) housed at the Taipei Zoo over a 20-yr period (1991–2011) were collected and analyzed for this study. The most common diseases affected the gastrointestinal system and the skin. Parasitic etiologies accounted for greater than 85% of these diseases, and coinfection was common. Coccidia and lice were the most common endo- and ectoparasites, respectively. High mortality was noted in serows less than 1 yr old associated with parasitism. The results from this study could provide vital information on disease prevention and species management, which may greatly help in rehabilitation of captive and wild populations.