To develop an easily applicable prediction rule for asthma in young adulthood using childhood characteristics.A total of 1,055 out of 1,328 members of a Dutch birth cohort were followed from 2 to 21 years of age. Univariate and multivariate logistic regression analyses were used to evaluate the predictive value of childhood characteristics on asthma at 21 years of age. A prognostic function was developed, and the area under the receiving operating characteristic (ROC) curve was used to estimate the predictive ability of the prognostic models.Of the 693 responding subjects, 86 (12%) were diagnosed with asthma. Independent prognostic factors at ages 2 and 4 years were female gender (odds ratios (OR) 1.9 and 2.1; 95% confidence intervals (CI) 1.2–3.2 and 1.3–2.5), smoking mother (OR 1.6 and 1.6; CI 1.0–2.7 and 1.0–2.6), lower respiratory tract illness (OR 1.9 and 2.4; CI 1.0–3.6 and 1.4–4.0), and atopic parents (OR 2.1 and 1.9; CI 1.3–3.4 and 1.2–3.1). The predictive power of both models was poor; area under ROC curve was 0.66 and 0.68, respectively.Asthma in young adulthood could not be predicted satisfactorily based on childhood characteristics. Nevertheless, we propose that this method is further tested as a tool to predict development of asthma.