Penicillin (PCN) allergy has been vastly overdiagnosed, and too many people are incorrectly labeled as allergic to PCN, which affects their health by preventing the use of beta-lactam antibiotics. This investigation explores whether taking a careful history can eliminate the need for some to carry the PCN allergy label. A retrospective study of a focused history and PCN skin testing was done in a consecutive sample of a suburban allergy population of 319 patients who had a positive history of PCN allergy. The patients were divided into three groups based on PCN history: convincing, vague, and unacceptable. The convincing group had patients with impressive histories of PCN allergy likely to be immunoglobulin E-mediated. The vague group had unimpressive but plausible histories of PCN allergy. The unacceptable group were those patients with the PCN-allergic label who were either never exposed to PCN or the PCN reaction was too far-fetched to be believable. Out of 319 patients with a positive PCN allergy history, 135 (42.3%) patients were classified as convincing, 150 (47%) patients were classified as vague, and 34 (10.7%) patients were classified as unacceptable. Positive PCN skin tests were found in 19 of 135 (14.1%) patients in the convincing group, in 10 of 150 (6.7%) patients in the vague group, and 0 of 34 (0%) patients in the unacceptable group. The finding that 6.7% of patients with a vague PCN allergy history had positive skin tests suggests that skin testing is necessary in this group. The PCN-allergic label in the unacceptable group had been unchallenged by 33 primary care physicians and 9 allergists. This study suggests that physician acceptance of unwarranted PCN-allergic labels is not uncommon, and that such labels can be removed without skin testing.