Early childhood risk factors for current sensitization were investigated by use of cross-sectional data of a longitudinal study in Southwest Germany. Information was gathered by questionnaires from 1812 families of whom 1470 children 6 to 8 years old were tested by means of a skin prick test (SPT) with seven aeroallergens. Groups with sensitization (n = 201; positive SPT to grass pollens 6.6%, Dermatophagoides pteronyssinus 6.5%, Dermatophagoides farinae 4.4%, cat dander 4.6%, any of the tested allergens 13.7%) are compared with children without sensitization (n = 1269). As risk factors for any sensitization parental atopy (odds ratio [OR]/95% confidence interval [95%CI]: unilateral 1.9/1.3 to 2.6; bilateral 2.8/1.5 to 5.2), low gestational age (1.9/1.1 to 3.2), and male gender (1.6/1.2 to 2.3) are statistically significant in multiple logistic regression. Former cat ownership is significantly related to sensitization to cat dander (2.7/1.4 to 5.5). Breast feeding, maternal smoking habits after the child's birth, prior exposure to pets, and social class are not important. In conclusion, our data suggest parental atopy, low gestational age, and male gender as independent risk factors for sensitization to aeroallergens at school age.