In Brazil, the learning of a second language (L2) by native Brazilian Portuguese speakers has been extensively explored, but studies on language processing and language interaction among bilinguals are quite recent. The late bilingualism of the first-generation immigrants has been studied mainly from the perspective of their difficulties in learning Brazilian Portuguese. Brazil has numerous communities of heritage speakers of many languages such as Japanese, German, Italian, Polish, Ukrainian, and Russian. However, the number of studies that focus on the bilingual speech of heritage speakers in Brazil is also quite limited. The aim of the current study is to evaluate the working memory in Russian-Brazilian Portuguese bilinguals as a function of the language and type of bilingualism. For this purpose, 49 first-generation Russophone immigrants and 28 older Russian heritage speakers, all residing in Brazil, were tested in Russian and Portuguese using a Month-Ordering task. We found that the working memory scores of the first-generation Russophone immigrants were not statistically different between both languages, but the median working memory score of the older Russian heritage speakers in Russian was 1.5-fold lower than in Portuguese. As next steps, we plan to verify the relation between the working memory capacity and narrative production abilities of the older Russian heritage-Brazilian Portuguese bilinguals in their heritage and societal languages.