Staghorn calculi (struvite stones) are a type of kidney stone that may occur with frequent kidney infections. They are called "staghorn" calculi because on X-rays they look like deer (stag) horns. Fewer than 10% of the people who have kidney stones have this type of stone.

Struvite stones can be more serious because they are large stones and an infection may be present. Medical treatment, including antibiotics and surgical removal of the stone, is usually needed. Women are affected more than men because of their higher risk for urinary tract infections.