The article discusses several still unpublished letters from Janina and Wacław Kościałkowski to Kazimierz Wierzyński, which have been found in the archives of the Polish Library in London. The article not only presents artistic and intellectual profiles of both the authors and the addressee, but also provides the analysis of the letters’ content and language. Thus, describes the archives as a supplemental yet important information on Janina Kościałkowska’s oeuvre.