Chylothorax is a rare cause of pleural effusion and occurs due to leakage of chyle into the pleural space. In most cases, it results from trauma, with malignancy accounting for most of the non-traumatic causes. Chylothorax resulting from immune reconstitution inflammatory syndrome (IRIS), during treatment ofMycobacterium aviumcomplex (MAC) infection, is an extremely infrequent cause of chylothorax, with only a handful of cases reported in the literature.