Examination of identification records from infected wood samples by three authorities in the GFR and of recent literature indicated * 2Serpula lacrimans* 1 to be a persistent and widely distributed decay organism. The heat tolerance of spores of eight strains of the fungus was tested to investigate environmentally acceptable control measures. A considerably greater heat dose was found to be required for spore eradication than that previously found necessary for destruction of mycelium (e.g., 4 hours at 100°C as opposed to 30 minutes at 50°). Differences in heat tolerance were found between the strains. Results indicated that to ensure eradication using hot air sanitation methods, a prolonged and thorough heat treatment of infected wood and brick work is essential; this cannot, however, be achieved in practice. -- AATA