In 212 sera from budgerigar and canary fanciers with symptoms of rhinitis and/or bronchial asthma, IgE antibodies against budgerigar feathers (Budf) or canary feathers (Canf) were determined. In 25 of 98 Canf-specific IgE antibody measurements, and in 28 of 154 Budf-specific IgE antibody measurements, a significant (6% or more binding of 125I-anti-IgE) level of specific IgE was found. In 3 sera with the highest levels of Canf- or Budf-specific IgE, IgE antibodies against sera from both birds were present. It is concluded that IgE antibodies against canary and/or budgerigar feathers are present in about 20% of canary and budgerigar fanciers with symptoms of atopic disease. Canary and budgerigar feathers contain IgE-binding antigens that are not present in the corresponding bird sera and droppings.