Sulfadiazine-associated urinary calculi have been described in HIV-positive adult patients but rarely in children. We report two pediatric cases of sulfadiazine-induced nephrolithiasis and review 45 adult cases from the literature. One had a hyper-IgM syndrome and was treated with sulfadiazine for cerebral toxoplasmosis, the other had toxoplasmic retinitis. Both developed multiple bilateral lithiasis with acute renal failure. Normalization of renal function and reduction of calculi size was rapidly achieved after discontinuation of sulfadiazine, hyperhydration, and alkalinization. Bilateral ureteral stents were required in one patient because of anuria.