Tuberculosis (TB) and lung cancer are the leading cause of mortality and morbidity in the world. Burden of TB is significantly high in developing countries causing serious public health concern, and incidence of lung cancer is also increasing all around the world with high mortality. Pulmonary TB coexisting with lung cancer can mask the underlying disorder producing diagnostic dilemma resulting in delay in diagnosis leading to decreased survival of the patients. Here we report a rare case of a 66-year-old male diagnosed microbiologically confirmed TB along with coexisting small cell neuroendocrine carcinoma of lung presenting with SIADH.