The concerns on indoor contamination by semivolatile organic compounds (SVOCs) are increasing. Because of the high boiling points in the range of 260–380°C, SVOCs are considered to vaporize poorly under living conditions. However, a wide variety of SVOCs were detected in indoor air and house dust in previous studies. Indeed, we found SVOCs frequently in both air and dusts of residential dwellings in Sapporo city in 2006. Among SVOCs, there are a number of findings indicating that phthalates and pesticides use associated with allergy or bronchial obstruction. The adjuvant effect of phthalates, particularly monoesters, was shown in animal experiments and the association between allergy prevalence and exposure to phthalates or indoor materials containing plasticizers was observed in previous epidemiological studies. Regarding pesticides involving organophosphates and pyrethroids among others, the association of pesticide use with asthma or chronic bronchitis was observed in commercial pesticide applicators or farmers. Because SVOCs were often found in air and house dust of residential dwellings, the risk of SVOC exposure should be assessed in the Japanese general population.