Mould growth can deteriorate indoor air quality in buildings. To alleviate the problems in the built environment, accurate understanding of the risk factors associated for mould infestation is required. This study aims to evaluate current status of mould growth problems in residential buildings in Korea. Both the physical characteristics of buildings and the behaviour of occupants have been studied as risk factors. In this study, a questionnaire survey has been conducted randomly on a national basis. A total of 314 completed questionnaires were collected and processed for statistical analysis. The relationship between mould growth and activity factors was analyzed. As a result, about 30% of residential buildings in Korea reported mould problems. However, the types of residential buildings did not show a statistically significant difference in the ratio of mould problems. Keywords：Mould growth, Mould problems, Residential buildings, Risk factors, Questionnaire survey