Twenty nine infants (8 females and 21 males) were included in our study. The beginning of the study started at least three weeks after the first bronchiolitis episode. Pulmonary function test was realized using an infant specific body plethysmography (Babybody, Erich Jaeger, Germany). Same tests were performed at 18 and 24 months. At 30 and 36 months, pulmonary function was evaluated by measuring respiratory resistances using oscillometry and occlusion systems (Masterlab-IOS, Erich Jaeger, Germany). If measured data showed an obstruction, a bronchodilatator was inhaled to assess reversibility. When results were normal, a bronchial provocation test, using inhaled metacholine, was performed.