The Rusyn language of the Carpathian Mountains is an East Slavic language (along with Russian, Belarusian and Ukrainian) close to Ukrainian. It is spoken in the Transcarpathian Region of Ukraine, in eastern Slovakia, southern Poland (where it is often called łemkowski 'Lemko', from their characteristic word lem/лєм 'only'), and Hungary. In Ukraine, Rusyn is often called a dialect of Ukrainian, but speakers are frequently reported to consider themselves distinct from Ukrainians.

Attempts to standardize the language suffer from its being divided between four countries, so that in each of these countries there has been devised a separate orthography (in each case with Cyrillic letters) and grammatical standard, based on different Rusyn dialects. The cultural centres of Carpatho-Rusyn are Prešov in Slovakia, Uzhhorod and Mukacheve in Ukraine, Krynica and Legnica in Poland, and Budapest in Hungary. Many very active Rusyns also live in Canada and the USA.

It is very difficult to count the speakers of Carpatho-Rusyn, but their number is sometimes estimated at almost a million, most of them in Ukraine and Slovakia. Rusyn has been recently recognized as a minority language in Slovakia, enjoying the status of official language in municipalities where more than 20% of the inhabitants speak Rusyn.