Lenvatinib prolongs the survival of patients with advanced thyroid cancer. At initiation of lenvatinib therapy,advanced thyroid cancer patients frequently have lung metastasis and are vulnerable to pulmonary complicationsdue to concealed lung damage caused by previous therapies including radioactive iodine (RAI) therapy. Among24 patients treated with lenvatinib, pulmonary events were observed in three patients with lung metastasis,including one with interstitial lung disease (ILD) and two with pneumothorax. One patient who was previouslytreated with 750 mCi RAI developed uncontrolled ILD after lenvatinib therapy and died of respiratory failure. Twopneumothorax cases had previous cavitation of metastatic lung nodules. Pneumothorax resolved spontaneouslyin both patients. Pulmonary events in patients with lung metastases treated with lenvatinib are uncommon andmanageable in most cases, but may be fatal if detection and management are delayed. Special attention shouldbe given to patients with lung metastasis treated with high cumulative dose of RAI therapy or cavitary changesthat develop after lenvatinib therapy.