In the last 25 years a conspicuous amount of plane glass – windowpane fragments – has surfaced on archaeological sites from the Viking Age. These finds have not received scholarly attention as they are not recognised as a genuine prehistoric (i.e. pre-1050 Scandinavia) occurrence. This paper aims to investigate a select group of archaeological localities that all have a significant amount of glass objects and fragments, and which also serve as mainstays for continental influences, commercial trade, as well as ritual activities. It offers the study of the chemical composition of these windowpane fragments, their distribution, provenience, and discusses their potential use as windows in Viking Age Scandinavia. Based on the chemical composition of the analysed plane glass (via LA-ICP-MS) the paper argues, firstly, that the glass most likely should be dated to the 9th to 11th centuries; secondly, that there are two possible import paths of raw material with one recognized at the early emporia based on east Mediterranean types of glass, and another with a continental type of glass found at the aristocratic sites. Finally, the paper argues that the windowpanes very likely could have been used in contemporary glassed windows placed in wooden buildings at these sites.