Ectomycorrhiza (ECM) is an ancient and prevalent symbiosis between plants and fungi, and is crucial for growth and survival for a number of plants. Host plants can form ECM with multiple fungi, yet little is known about the fine-scale structure of root associated fungi within single root systems. The motivation for this study was to increase our knowledge about the richness, diversity and spatial distribution of fungal root symbionts within single root systems. An entire root system of the ECM forming Bistorta vivipara was dissected, all root tips (2302) were sampled and their relative position mapped. A direct PCR approach followed by Sanger sequencing was used to identify the fungi using the ITS region as DNA barcode. Fungi were succesfully amplified and sequenced from 26.0 % of the root tips. The remaining root tips were not included due to lack of amplification, mixed templates or poor sequence quality. A total of 57 operational taxomic units (OTUs) were recovered when using a 97.0 % sequence similiartiy threshold for clustering, although estimates indicate that a higher richness exists. Basidiomycetes dominated, occupying 82.1 % of the successfully sequenced root tips, with Thelephorales as the dominant order (54.6 %). The majority of the root tips (81.9 %) were occupied by ECM fungi. A few OTUs occupied a large proportion of the root system, out of which an OTU with affinity to Pseudotomentella was the most abundant (34.0 %). Multiple ITS genotypes were discovered within nine of the OTUs, which may indicate that severeal genets of some species are present within the root system. Although only about a quarter of the fungi occupying root tips could be identified, a clear spatial structuring of the root-associated fungal community was observed. The results presented indicate that a priority effect may be important in structuring the fungal community in the younger parts of the root system, while competition seems to be more important in the older parts. This study provides a glimpse into the fine-scale structuring of the root-associated fungal community of a full grown ECM plant.