Asthma is among the most frequent chronic diseases in childhood. Although numerous environmental risk factors have already been identified, the basis for familial occurrence of asthma remains unclear. Previous genome screens for atopy in British/Australian families and for asthma in different American populations showed inconsistent results. We report a sib pair study of a sample of 97 families, including 415 persons and 156 sib pairs. Following an extensive clinical evaluation, all participants were genotyped for 351 polymorphic dinucleotide markers. Linkage analysis for asthma identified four chromosomal regions that could to be linked to asthma: chromosome 2 (at marker D2S2298,P= 0.007), chromosome 6 (around D6S291, lowestP= 0.008), chromosome 9 (proximal to D9S1784,P= 0.007), and chromosome 12 (D12S351,P= 0.010). These linkage regions could be reproduced for all loci by analysis of total or specific immunoglobulin E (minimumPvalues at these regions were 0.003, 0.001, 0.010, and 0.015, respectively).