However, their efficacy is limited.2Sirolimus, an immunosuppressive agent, inhibits the mammalian target of rapamycin (mTOR), which regulates cell division, proliferation, and survival.3As an mTOR inhibitor, sirolimus suppresses lymphangiogenesis and is thought to regulate lymph production and leakage by decreasing lymphatic endothelial cell activity.3Herein, we report the case of an infant with Noonan syndrome who was treated with sirolimus for recurrent and refractory chylothorax and edema. The gene discussed is MTOR; the disease is Chylothorax.