Abstract Inuit infants have high rates of reported hospitalization for respiratory infection, associated with overcrowding and reduced ventilation. We performed a randomized, double-blind, placebo controlled trial to determine whether home heat recovery ventilators (HRV) would improve ventilation and reduce the risk of respiratory illnesses in young Inuit children. Inuit children under 6 years of age living in several communities in Nunavut, Canada were randomized to receive an active or placebo HRV. We monitored respiratory symptoms, health center encounters, and indoor air quality for 6 months. HRVs were placed in 68 homes, and 51 houses could be analyzed. Subjects had a mean age of 26.8 months. Active HRVs brought indoor carbon dioxide concentrations to within recommended concentrations. Relative humidity was also reduced. Use of HRV, compared with placebo, was associated with a progressive fall in the odds ratio for reported wheeze of 12.3% per week (95%CI 1.9-21.6%, P = 0.022). Rates of reported rhinitis were significantly lower in the HRV group than the placebo group in month 1 (odds ratio 0.20, 95%CI 0.058-0.69, P = 0.011) and in month 4 (odds ratio 0.24, 95%CI 0.054-0.90, P = 0.035). There were no significant reductions in the number of health center encounters, and there were no hospitalizations. Use of HRVs was associated with in improvement in air quality and reductions in reported respiratory symptoms in Inuit children. Practical Implications Reduced ventilation is common in the houses of Inuit children in arctic Canada, and is associated with an increased risk of respiratory infection. Installation of HRV brings indoor carbon dioxide concentration, as a marker of adequate ventilation, to within recommended concentrations, although relative humidity is also reduced. Installation of HRV is associated with improvements in indoor air quality, and a reduced risk of wheezing and rhinitis not associated with cold air exposure in young Inuit children. Further research is required to explore traditional Inuit cultural attitudes about air movement in dwellings.