The website GovernmentAttic.org (http://www.governmentattic.org) has released a declassified (and heavily redacted) copy of a 1981 FBI monograph titled "Soviet Use of the Polygraph":
http://www.governmentattic.org/6docs/FBI-Monogtaph-SovietUsePolygraph_1981.pdf
The document focuses on the KGB's use of polygraphs, which was limited.