The fingernails of a woman with pachyonychia congenita were ablated by several different methods. The most effective, most rapidly performed, and most acceptable method was vigorous curettage and electrofulguration of the matrices and beds of the nails. The responses to treatment suggest that the matrix, rather than the bed, is the site from which the abnormality of the nails develops in pachyonychia congenita. Removal of the nail beds is not necessary to prevent recurrence of deformed nails, but it may reduce hyperkeratosis in their sites.