We present here an interesting case of a 67-year-old man with 3 weeks history of lethargy, loss of appetite, generalised weakness and weight loss. Following thorough investigations, occult malignancy was ruled out. Hyponatraemia was a consistent finding which needed further classification. Additional workup including cerebral imaging and neurophysiological studies excluded cerebral vascular events and myopathies. Vasculitis screening was undertaken, and the diagnostic dilemma was revealed by the temporal arteries Doppler ultrasound which showed classical ‘halo sign’. Diagnosis of temporal arteritis was made and linked with syndrome of inappropriate antidiuretic hormone secretion, which appears to be a rare association with few instances on record. Patient was treated with high dose of prednisolone with marked improvement of clinical features.