Rare diseases, while individually rare, are common when considered collectively, affecting about one in 17 people across their lifetime. However, there is a lack of awareness of and education about rare diseases in nursing. To address this, the Global Nursing Network Rare Diseases (GNNRD) has been launched to connect nurses from within all fields of practice and at all levels of experience, with the aim of improving the lives of people with rare and undiagnosed diseases (RUDs). The GNNRD aims to empower nurses on a global scale through leadership, knowledge exchange and skill development and to provide a platform from which they can influence policy and advocate for patients and their families at regional, national and international levels. This article provides an overview of RUDs and some of the challenges experienced by patients and their families and describes the development and aims of the GNNRD.