This study evaluated the association of polymorphisms in the proximal promoter region IL10 rs1800896 (–1082G/A), rs1800871 (–819C/T) and rs1800872 (–592C/A) or in the distal promoter region IL10 rs1800890 (–3575T/A) with IOS results at a median age of 6.3 years in children hospitalised for bronchiolitis before six months of age. The gene discussed is IL10; the disease is bronchiolitis.