Longitudinal melanonychia associated with scleroderma is rare. This is paradoxical, as increased skin pigmentation is frequent in the latter disease. This article reports 4 cases of longitudinal melanonychia that were found concurrently with various types of localized scleroderma. These 4 cases may be a coincidental finding despite the fact that pigmentation is so frequent a manifestation of scleroderma. In 2 cases, biopsy specimen of the nail matrix showed well-defined melanocytes without cellular atypia. This, in keeping with the pigmentation of scleroderma, appears to result from the functional activation of the matrix melanocytes.