Melanonychia describes a brown or black pigmentation of the nail plate caused by the presence of melanin. In this article, we review possible causes of melanonychia and discuss the main problems of management of patients with this condition. The goal in the management of melanonychia is early diagnosis of melanoma of the nail matrix and bed. Melanoma of the nail bed is also known as subungual melanoma. We discuss clinical, dermoscopic features that may help the clinician in selecting lesions that should have excisional biopsy and evaluate different options for the excision. Addressing melanonychia is still a difficult task, and the correct management of pigmented bands in children is far from established. Dermoscopy is possibly a useful tool but the real benefit of this technique, screening lesions to determine which ones need to be removed, remains to be proven.