A previous study has reported a strong association of a variant (Ile181Leu) of the beta-subunit of the high-affinity IgE receptor (Fc epsilon RI-beta) with allergic asthma bronchiale in a random patient sample. Based on their results the authors concluded that Fc epsilon RI-beta may be the maternally inherited, atopy-causing locus. We have investigated 40 unrelated atopic patients, 30 with allergic asthma and 10 with atopic dermatitis or allergic rhinoconjunctivitis along with some of their relatives for the presence of Ile181Leu by nucleic acid sequence analysis and/or hybridization with mutation-specific oligonucleotide probes. None of the probands showed this mutation suggesting that its association with atopy may be restricted to certain populations or occur at lower frequency than reported.