We evaluated two children with allergy to egg-white protein (ovalbumin) who had generalized urticaria, angioedema, and respiratory difficulty after immunization with live rubeola vaccine. In both patients, serum IgE reactive with ovalbumin-related antigens in the vaccine was demonstrated. Subsequent evaluation of 24 children with ovalbumin allergy revealed that those who had positive ovalbumin skin tests, but no clinical reaction to egg white, were skin test negative on prick and intradermal testing with measles vaccine and were safely immunized. They had no detectable IgE directed against the rubeola vaccine, although IgE directed at ovalbumin was present. Six patients who had severe allergic hypersensitivity reactions on exposure to ovalbumin had IgE antimeasles vaccine antibody and had positive reactions after intracutaneous or intradermal testing with the vaccine. These patients were safely immunized with increasing volumes (0.05 ml increments every 20 minutes) of measles vaccine to receive the full dose. These studies suggest that children with severe allergic hypersensitivity to egg white should be screened with an intracutaneous test prior to immunization with measles vaccine; however, children who have positive skin tests but no clinical reaction to ovalbumin exposure are at minimal risk for hypersensitivity reactions to measles immunization, as previously reported.