This paper examines Chaho’s Grammaire euskarienne (1836). After explaining how the work was published, its structure is presented and the content of its three parts is explained. Even though Chao’s ideas about languages and Basque are contemporary (above all their natural aspect), there is no doubt that this is an original work. The theory of the single verb, which became highly successful over the decades to come, is clearly presented in Chaho’s analysis. The linguistic data offered, in particular the verb paradigms and their classification, are his and are based on the dialect of Zuberoa (Soule).