Dexmedetomidine is an α2-adrenergic sedative–hypnotic medication used as an adjunct to general anesthesia. While experimental studies in animals have demonstrated a mild diuretic effect of dexmedetomidine, only recently have case reports described dexmedetomidine-induced diuresis in humans. Interestingly, the majority of such cases have involved patients undergoing spinal fusion surgery. Here, we report a case of a 30-year-old woman undergoing cervical spinal fusion surgery who experienced a massive diuresis starting 30 minutes after receiving dexmedetomidine intravenous infusion. We discuss the differential diagnosis and synthesize the current literature on this rare effect.