1. There exists in the zone of Coto and Golfo Dulce (boundaryzone between Costa Rica and Panama) a dermatosis which is contagiouswith tendency towards an epidemic character.
2. The clinicaland serological characters and the influenceof the arsenicaltreatment leads one to believe that it it aspirochetosis.
3.The form of the papules, their color, their mode of evolution,make one think of yaws.
4. Failure to find the spirochetewas probably due to the ratheradvanced state of the disease.
5. The cases of yaws herein described, if correctly diagnosed,appear to be the first to be reported from Costa Rica.