The article is devoted to English-French lexical interference in teaching English for specific purposes to students of International Relations who study French as their first foreign language. A pilot study was conducted, in which typical lexical errors of Russian-speaking students who study English as their second foreign language were identified. The results of the study indicate that students’ typical mistakes are caused by English-French lexical interference. The authors conclude that a special teaching and methodological complex could be effective for students’ lexical skills development, their vocabulary expansion and the reduction of errors caused by language interference. © 2019, Slovenska Vzdelavacia Obstaravacia. All rights reserved.