Data from a nationwide survey on the status of the Swedish residential building stock and indoor air quality wasplaced in the public domain by the National Board of Housing, Building and Planning of Sweden. The currentresearch investigates the indoor humidity conditions in Swedish residential buildings, single-family houses andapartments, assessing the measurements from the extensive BETSI-survey against adjusted relative humiditylevels based on existing norms and Standards. The aim of this study is to investigate associations and correlationsbetween relative humidity levels and multiple building and system characteristics, occupancy patterns and behaviors and health symptoms-complaints. The analysis uses 13 categorical and 9 continuous variables-parameters of the examined dwellings.Analysis shows that low indoor relative humidity is a realistic issue in Swedish dwellings during the heatingseason. The issue is more prevalent in apartments than single-family houses. In addition, low indoor relativehumidity seems to be more extensive in dwellings with higher indoor temperature, smaller volume, higherventilation rate and frequent airing practices, lower number of occupants, constructed mainly after 1985, in citysuburbs and in the northern parts of the country. The developed multinomial logistic regression model maypredict very accurately the relative humidity level of the Swedish dwellings, during heating season. This analysisoffers additional evidence to the scientific literature for possible correlation of low relative humidity with specifichealth symptoms, complaints and disturbances.