The complex relationship between ventilation rate and indoor air quality greatly complicates research on the associations of ventilation rates with health outcomes and perceived air quality. Many of the studies have failed to control for important potential confounders or have incompletely characterized the study buildings and study methods. The difficulties and inaccuracies in ventilation rate measurements have also served as a barrier to this area of research. Almost all the studies included in this review found that ventilation rates below 10 Lsª1 per person were associated with a significantly worse prevalence or value of one or more health or perceived air quality outcomes. Most of these studies have been conducted in office buildings. Available studies further show that increases in ventilation rates above 10 Lsª1 per person, up to approximately 20 Lsª1 per person, are sometimes associated with a significant decrease in the prevalence of SBS symptoms or with improvements in perceived air quality. Data from multiple studies also indicate a dose-response relationship between ventilation rates and health and perceived air quality outcomes, up to approximately 25 Lsª1 per person; however, available data are not sufficient to quantify an average dose-response relationship. The less consistent findings for relationships in the range above 10 Lsª1 per person are compatible with the prediction that benefits per unit increase in ventilation would be likely to diminish at higher ventilation rates and, thus, be more difficult to detect epidemiologically. Only five studies were conducted in hot humid climates; thus, the results of this review apply primarily to moderate and cool climates.