Sain (Persian: سيين)[a] is a village in Arjestan Rural District of Sabalan District in Sareyn County, Ardabil province, Iran.

At the time of the 2006 National Census, the village's population was 839 in 179 households, when it was in Sabalan Rural District of the former Sareyn District in Ardabil County.

[6] The 2016 census measured the population of the village as 947 people in 276 households.

Sain was the most populous village in its rural district.

This Sareyn County location article is a stub.