The aim of the present work was to investigate the potential for territorial and dispersive clonality in natural populations of the postfire root rot ascomycete Rhizina undulata. Population studies based on vegetative compatibility tests were done with strains isolated from individual sporocarps at five burned sites in three different localities (separated by 20-40 km) in the Curronian Spit of western Lithuania. Among a total of 103 strains, the tests identified 14 distinct vegetative compatibility groups (VCGs) of R. undulata, 13 of which were represented by 2-48 strains and three were encountered at 2-4 different sites. Occurrence on spatially separated sites of the same VCG of the fungus indicated a presence of dispersive clonality in R. undulata populations. On a local scale clusters of vegetative compatible sporocarps usually occupied discrete territories, implying territorial clonality. The two largest VCGs covered areas up to 7 and 3 m across. The results show that both dispersive and territorial clones are characteristics of natural populations of the fungus.