Acute interstitial nephritis (AIN) classically presents as acute kidney injury most often induced by offending drugs. Less frequently it is secondary to infections, autoimmune disorders, or idiopathic conditions. Development of drug-related AIN is not dose dependent and a recurrence can occur with re-exposure to the drug. We present a 50-year-old male with treatment resistant schizoaffective disorder who developed clozapine-induced AIN, confirmed with kidney biopsy within 2 months of taking this medication. His kidney function improved with removal of the drug and treatment with steroids. However, his kidney function was again significantly impaired when rechallenged with even a lower dose of clozapine a year later. Kidney function returned to baseline after stopping clozapine. Monitoring of kidney function during clozapine therapy is essential to therapy. Prompt diagnosis is imperative as discontinuation of offending agent can prevent acute kidney injury.