ENThe language of Yotvingians belongs to the group of Western Baltic languages and is closely related to the Prussian language. Some authentic Prussian words are written in so-called Elbing Vocabulary. The author claims that the language of the Catechisms (1,2), which are considered to be the monuments of Old Prussian, is the sub-dialect spoken in Sambia. He thinks that it is closely related to the language of Yotvingians or it is the language of Yotvingians. He tries to substantiate his thesis.