Zarasai County (, , ) was one of the counties of the Russian Empire.
Established 1795 under Vilna Governorate, it was transferred to the Kovno Governorate in 1843. Soviet authorities formally abolished it in 1924.
At the time of the Russian Empire Census of 1897, Zarasai County had a population of 208,487. Of these, 49.8% spoke Lithuanian, 16.8% Belarusian, 12.7% Yiddish, 9.9% Russian, 8.9% Polish, 1.8% Latvian and 0.1% German as their native language.