Making a medical diagnosis in an elderly person presenting with first time psychiatric symptoms can be challenging. A 61 year old lady presented with 4 years history of tactile hallucinations in her legs and delusions of persecution, and 2 weeks history of depression and mild cognitive impairment. There were no other significant physical findings, except for dysarthria and fine bilateral hand tremors. As patient had no prior psychiatric history, she was investigated for differential diagnoses of late-onset schizophrenia, psychotic depression and early dementia. A thorough investigation for concomitant medical illnesses was done which revealed low serum calcium, high serum phosphate and relatively low serum parathyroid hormone levels. A diagnosis of Fahr's syndrome (FS) was made based on history, hematological findings of idiopathic hypoparathyroidism and bilateral basal ganglia calcifications (BGC) on neuroimaging. Treatment of FS is non-specific and mainly symptomatic. This patient improved with treatment comprising antidepressant, antipsychotic and calcium supplement.