Onychomatricoma is a subungual tumor that is clinically characterized by banded or diffuse thickening, yellowish discoloration, splinter hemorrhages, and transverse overcurvature of the nail plate. It is often and easily misdiagnosed because the condition is not well known and rarely has been described. We report the case of a 45-year-old man with a subungual tumor on the right index finger that fulfills the criteria of onychomatricoma.