This article presents the concept of Jewish Lithuanian as a range of post-Yiddish varieties spoken by some Jews in Lithuania and seeks to synthesise findings in contemporary ethnolect studies and in the field of Jewish language research. The legitimacy of the term "ethnolect" is questioned by some researchers; however, it is argued that contemporary ethnolect research concentrates on postmodern urban immigrant communities in the west, which are very different from the situation of Jews in contemporary Eastern Europe. It is argued that language and identity matters are more complex than just "Jewish", "Lithuanian" or "assimilated Jew". Jewish Lithuanian exhibits realisation of diphthongs and palatalised consonant different from that in mainstream Lithuanian. These features are traceable back to Yiddish. There is very little Yiddish impact on the lexical level; as for morphosyntax and pragmatics, more data are needed. The informants exhibit a high degree of linguistic awareness and their metalinguistic comments provide relevant information. Different from other post-Yiddish varieties, Jewish Lithuanian is not a transitional stage towards monolingualism: the speakers remain multilingual and code-switching between varieties of Lithuanian, Yiddish and Russian is a common phenomenon. (Contains 1 table and 11 notes.)