Hospital medicine was introduced to Taiwan in 2009. Starting with the integration of teams and departments within a hospital, hospital medicine was gradually expanded to inter-hospital collaborations. Under the framework of the hierarchy of medical care, vertical referrals involving continuous care in the upstream, midstream, and downstream were achieved, establishing an example for the medical network. At present, over 20 hospitals in Taiwan participated in the trial project of the Ministry of Health and Welfare, and they developed hospital and community referral models with local features. This study used the Department of Hospital Medicine of Taipei City Hospital as an example to share the experiences of and challenges faced by making referrals in metropolitan areas, hoping that hospitals of every level can co-prosper and collaborate to become the protector of people’s health.