Metastasis to the pituitary gland and iris is rarely seen in cancer patients. Breast cancer and lung cancer are the most common tumors that metastasize to these sites. Most lung cancer patients have non-small cell lung cancer and metastasis of small cell lung cancer to the pituitary gland and iris have been very rarely reported in the literature. Here we present a case of iris metastasis and pituitary gland metastasis which caused diabetes insipidus in a patient with small cell lung cancer.