This article presents data on Kongemose culture material which has been found in Lithuania but not yet studied. Based on material from west, east and south Lithuania Stone Age settlements, the aim is to acknowledge the existence of this culture’s technology during the Atlantic period in the east Baltic region. The use-wear method was also used for a more detailed analysis. The results of the article contain versions of the emergence and development of rhombus-shaped arrowhead technology in the east Baltic during the Stone Age period.