In this article, the question is raised whether the personal names used in medieval documents differed from the names used in oral communication within the local communities of that time. The author concludes that in Jämtland, a province in Mid-Scandinavia with a rather good source material for investigating this question, there was a difference. In everyday life, a lot of men were apparently called by their hypocorisms (nicknames), i.e. weak forms of their given names, e.g. Pale, Gumme, Gisle instead of Pavel, Gudhmund, Ødhgisl. In written, official documents, the given names were preferred. These conclusions are drawn from analyses of male names occurring in medieval place names (which are expected to reflect a naming custom close to everyday life) and in the extant documents from c. 1300-1550. Some comparisons with other areas are made. Female names are not dealt with in this study.