Nephrogenic diabetes insipidus (NDI), a rare cause of polyuria and polydipsia in children, is usually managed with medications and careful monitoring of water intake. We present a child who was incidentally found to have right hydronephrosis secondary to ureteropelvic junction obstruction, and was subsequently also diagnosed with NDI. After being medically managed, he underwent open right pyeloplasty. His polydipsia abated within 1 month of surgery, and he has done well off of medications since that time. NDI resolution after correction of obstructive uropathy in adults has been reported, but this represents a novel case in pediatrics.