Diabetes insipidus (DI) is a rare complication of systemic cancer disease caused by hypothalamo- pituitary gland area metastasis. Extended diagnosis must be performed especially in patients with DI as predominant symptom. Breast and lung cancer are the most common malignancies giving metastases to pituitary gland (MPs). Conjecture of MP is usually based on clinical and radiological assessment. We are going to present two case reports of patients with DI without incriminating history towards malignancy. Lung cancer in Patient 1 and disseminated squamous cell carcinoma with likely primary lesion from the lungs in Patient 2 were finally established.