The role of atopy in the development of asthma has become increasingly recognised. We have been prospectively following a birth cohort of children of atopic parents to document the development of atopic disease. Our aim in this study was to document the natural history of BHR and wheeze at 10 years of age and to relate this to atopy. We reviewed 47 of our original cohort of 79 infants at 10 years of age and documented their clinical history of atopic disease and performed allergen skin prick tests and BHR to histamine. Thirty-three (70%) children wheezed at some time during their 10 years of life, with 13 commencing in infancy. Twenty-two children (47%) had current wheeze at 10 years of age. Wheeze in infancy was a poor predictor (RR 1.23, CI95 0.66-2.23) of current wheeze while wheeze commencing after infancy was a good predictor (RR 2.89, CI95 1.45-5.2). In contrast both atopy in infancy (RR 2.94, CI95 1.92-4.53) and current atopy (RR 3.58, CI95 1.43-9.03) were strong predictors of current wheeze. Analysis of BHR confirmed the importance of atopy in predicting its occurrence and severity. Sensitisation to D. pteronyssinus appeared to be the strongest predictor of both current wheeze and BHR. These observations confirm the importance of atopy in predicting outcome in children with asthma and suggest that wheezing in infancy and wheezing in later childhood may have different pathogenetic mechanisms.