We report the first case of generalized lymphatic dysplasia and trisomy 21 presenting with nonimmune hydrops fetalis. This infant showed intractable chylothorax, chylous ascites, and periodic bouts of edema. A karyotype analysis revealed Robertsonian trisomy 21: 46,XY,t(14q21q)(q10;q10) +21. This patient died of multiple organ failure at 400 days of life, despite the management of chylous effusions. The lymphoscintigraphy and histopathological findings led to the final diagnosis of generalized lymphatic dysplasia, which might also contribute to the development of hydrops. Refractory chylothorax in trisomy 21 patients may emphasize the need for intensive scrutiny of lymphatic disorders.