The choice of Florina as field study is due to its situation in the border zone of three countries [Greece-Albania-fyrom (Former Yugoslav Republic of Macedonia)], to the composition of its population and to the development of movements of minorities in the area. In the last ten years this region (Greek western Macedonia) drew therefore the attention of some ten social anthropologists interested in the recomposition of national frontiers in the European South-East. The author describes his four-year ethnographical field experience in Florina. His study bears on three points: the relation between the forms of anthropological and autochtonous knowledge; the way anthropologists perceive their work and lastly their processes of self-definition.