Pieces of sapwood of pine were buried in soil outdoors for two weeks. Thereafter, the samples were incubated at a high relative humidity for four weeks. The aim of the study was to show the microbiological consequences of soil-contaminated building material being exposed to a prolonged period of high humidity. Microbial activity can be responsible for the production of bad (”mouldy”) odour. Pieces of uncontaminated wood and pieces of wood exposed to sterile soil were used as controls and were incubated in the same way as the soil-contaminated pieces. The results show that pieces which had been in contact with soil generate a bad odour while control samples did not. Chemical analysis (GS-MC) showed that the odorous substance geosmin could be detected only from pieces which generated bad odour. The results lead to the conclusion that it is important to protect wood intended for building purposes from soil contamination. Such a precaution could reduce the risk for bad odour in buildings.