endotoxin exposure wheezing and rash in infancy in a new zealand birth cohort background wheezing in infancy is common and is associated with small lungs viral respiratory tract infection and environmental tobacco smoke exposure recently increased levels of endotoxin in the domestic environment have also been associated with infant wheezing particularly among infants with a family history of atopic diseaseobjective to explore associations between exposure to endotoxin at 3 months of age and reported symptoms of wheezing rhinitis itchy scaly rash and atopy at 15 months in a birth cohort of 881 new zealand childrenmethods using standardized methods a 1m2 site from the bedroom floors of the 3monthold infants was sampled and analyzed for endotoxinresults wheezing was significantly associated with higher endotoxin levels odds ratio or 154 95 ci 103230 particularly among infants with a parental history of allergic disease or 167 95 ci 107260 higher endotoxin concentrations were also strongly associated with recurrent itchy rashes or 187 95 ci 114305 particularly among infants who were atopic or 464 95 ci 1561377 or had a parental history of allergic disease or 210 95 ci 122361conclusion domestic endotoxin was associated with reported airway and skin symptoms in this large group of new zealand infants the role of endotoxin in the development of respiratory and skin disease in infancy deserves further studyclinical implications reducing domestic endotoxin exposure might reduce infant wheezing and atopic dermatitis but the longterm benefits of this remain unclear