Mycelial interactions on Hagem agar between 156 isolates of Stereum sanguinolentum obtained from wounded Picea abies or from slash in 12 sample plots located in Sweden, Finland and Lithuania revealed 97 vegetative compatibility groups (VCGs). Of the 23 VCGs that consisted of two or more (maximum, 23) isolates, 13 came from different sample plots, and sometimes from two or all three countries, whereas 10 were confined to a single sample plot. Some variation was observed in cultural characteristics among isolates belonging to the same VCG. Within a sample plot compatible isolates were randomly distributed indicating that distances up to 180 m in a forest stand have little influence on spread of S. sanguinolentum VCGs. Proportions of compatible pairings decreased among isolates collected within the bigger spatial scale. Occurrence of compatibility and consequent grouping of the isolates into VCGs was more pronounced in Swedish populations then Finnish and Lithuanian populations.