This report describes a 68-year-old Chinese man who was diagnosed with Good syndrome 6 years after initial presentation when he underwent thymectomy. He presented with recurrent pneumonia, diarrhoea, weight loss, and visual symptoms. Extensive examination for anaemia and neutropenia was done, yet no conclusive diagnosis could be derived. During his last admission for pneumonia, his history of AB thymoma suggested the possibility of Good syndrome. Immunological testing revealed low T cells, absent B cells, and low immunoglobulin M and immunoglobulin G levels. Moreover, he had histologically identified cytomegalovirus pneumonia, cytomegalovirus colitis, and fundoscopic features of cytomegalovirus retinitis. He was treated with a 2-week course of intravenous ganciclovir, lifelong oral valganciclovir, and monthly immunoglobulin infusion. It took 6 years for the diagnosis to be established, therefore, early attention and vigorous search for such potentially treatable conditions in post-thymectomy patients presenting with recurrent infections is recommended.