Onychomatricoma is an uncommon benign tumor of the nail matrix, with peculiar clinical and histologic features and electron microscopic findings. The main clinical signs are longitudinal ridging, yellow coloration along the entire length of the nail plate with splinter hemorrhages in its proximal portion, and a tendency towards transverse overcurvature of the affected nails. We report onychomatricoma associated with onychomycosis in the same nail in a 4-year-old girl.