Ingestion of indoor dust has been highlighted as an important pathway of exposure to brominated flame retardants. Hence, polychlorinated biphenyls (PCBs) were determined in indoor dust from homes in Amarillo/Austin, TX, USA (n=20; median concentration=200 ng Sigma PCB g(-1)); Birmingham, UK (n=20; 48 ng Sigma PCB g(-1)); Toronto, Canada (n=10; 260 ng Sigma PCB g(-1)); and Wellington, New Zealand (n=20; 46 ng Sigma PCB g(-1)). Concentrations in Canadian and US samples were statistically indistinguishable, but exceeded significantly (p<0.05) those in both New Zealand and UK dust. Principal component analysis revealed that while UK samples were enriched comparatively in lower molecular weight congeners; samples from other countries contained proportionally more mid-to-high molecular weight congeners. Concentrations of PCBs determined in air from the same 10 Canadian homes showed concentrations (median=4.9 ng Sigma PCB m(-3)) higher than those reported previously for UK homes (1.8 ng Sigma PCB m(-3)). Interpretation of these data alongside that for dietary exposure from other studies suggest that indoor exposures (i.e. air and dust combined) may be a significant contributor to overall exposure for the majority of the population - ranging from 4.3% to 87% in adults and 1.6-73% in toddlers. While inhalation is the principal indoor pathway under a typical dust ingestion scenario, exposure via dust ingestion exceeds that from either inhalation or diet for a small proportion of North American toddlers.