Phenylketonuria is a rare genetic disorder where the body lacks the enzyme needed for the breakdown of phenylalanine in the metabolic pathway. This leads to the accumulation of phenylalanine and its ketones in the body, which are then excreted in urine, causing a series of symptoms. The disease has a distinctive smell of urine, hence also known as ‘urine odor disease.’ Every newborn should undergo a urine test for early diagnosis and treatment. Treatment primarily involves a low-phenylalanine diet and targeted treatment after confirmation. Parents and caregivers also need to learn how to manage this special diet and monitor the patient’s progress.