Isolates of Chondrostereum purpureum were characterised on malt agar by rapid growth of white, flat, velvety to cottony mycelium and formation of yellow fruitbody crusts with apiculate basidiospores. The presence of cystidia was diagnostic, but not a reliable taxonomic character. Above 33 °C isolates exhibited a differential growth response and only three failed to grow following 20 d incubation at 36°. Tolerance of high temperature was not correlated with RAPD banding patterns nor geographic origin. All isolates were pathogenic to willow, poplar and apple regardless of their original host, locality or RAPD profiles. No zones of demarcation were observed following infection of wounds by multiple isolates. RAPD banding patterns exhibited considerable diversity, enabling discrimination of isolates with single primers, and this was indicative of the extensive genetic diversity within the NZ population. No RAPD banding combinations specific to host species or locality were observed. An explanation is given for the wide dissemination of C. purpureum isolates throughout NZ.