The authors present three familial cases of Schonfeld's type I pachyonychia. This syndrome represents the association of pachyonychia with palmoplantar keratodermia, frictionnal keratosis and bullae, hyperidrosis, oral leucokeratosis. This genotype is present in the remaining family. Traumatisms produce or increase several symptoms as: a) palmoplantar keratodermia: voluminous callus confined to site of pressure; b) hyperkeratosis of the nails, with hyperplasia and papillomatosis of the nail bed and the hyponychium due to the frequents microtraumatisms of the finger-pulps; c) oral leucokeratosis. The authors describe the painful character of the palmoplantar lesions: walking and working with the hands are very difficult. They assert the outstanding action of aromatic retinoid (RO 10.9359) which entertains a dramatic improvement of the palmoplantar and pachyonychia lesions, the decrease of the pain. Now, the patient life is normal. In these three cases, an hyperuricemia is associated: this feature is probably a fortuitous association. One of these patients has a Lesch-Nyhan's syndrome.