Factual literature occupies a significant place in contemporary Lithuanian literature for children. It is especially relevant to a teenager reader; factual literature meets the need for scientific knowledge, documentary, non-fiction text. Factual literature manifests through diverse genres, types. Traditionally, a very pronounced theme of factual literature is nature. This article especially broadly deals with depiction o f a swamp as a natural object in factual Lithuanian literature for children. Popular scientific texts on swamp, a mysterious and intriguing object, speak to a child-reader from works o f encyclopaedic character (e.g. "Enciklopedija vaikams apie Lietuvą", Vilnius, 2001) or similar to them (e.g. Alis Balbierius, "Jaunojo gamtininko kalendorius", Vilnius, 1995; Stasys Gliaudys, "Gamtos namuose", Šiauliai, 2001). Publicistic style, abundance of scientific data, an objective tone of conversation - all these are the characteristic features of publications o f such kind. Perhaps the most numerous group of texts on swamp is scientific fiction publications. Their genres vary: pictures, miniatures, sketches; sometimes the genre is defined abstractly - "stories about nature". Majority of writers, authors of many books, write within this field: Leonas Grudzinskas, Gediminas Isokas, Juozas Šokas, Bronius Šablevičius, Henrikas Gudavičius and others.The authors strive to tell their stories suggestively, seek artistic expression, authentic experience grounds. Scientific fiction texts are the rarest; they match both fictional narration and scientific facts about fauna, flora, etc of Lithuanian nature (including swamps). The most outstanding piece of literature is a novella "Paukštulis - ežero vaikas" (1987) by Vytautas Nedzinskas; it tells about Žuvintas reserve and Žilvinas Dilys, a boy from Kaunas, a naturalist who investigates it. The novella shows adventures, artistic pictures of nature. Planes of both science and fiction are matched quite subtly. Moreover, books of factual character for children are usually written by practitioners - naturalists, scientists, and reserve staff