The aim of this article is to present a set of rules applicable in translation of Polish imperfective past tense to French language. We emphasize certain phenomena peculiar to Slavic languages, which are in general difficult to translate. The article is composed of two parts. The first one offers specific rules of translation based on the theory of aspect of Stanisław Karolak, which can be directly applied in text translation. The second area of study is devoted to the analysis of chosen connotations of imperfective forms in Polish language and offers sample solutions to the problems of translation.