Latex has been documented as causing immediate hypersensitivity reactions ranging from contact urticaria to severe anaphylaxis. Latex proteins may also act as airborne allergens causing rhinitis and asthma. The prevalence of occupational asthma due to latex gloves among health care workers is unknown. We surveyed the employees of a primary care hospital including nurses (n = 201), members of the cleaning staff (n = 50), and laboratory technologists (n = 38). In the initial part of the study, a questionnaire and skin-prick tests with latex and common inhalant allergens were administered to 273 of 289 (94%) members of the target population. Thirteen of the 273 subjects (4.7%; 95% CI: 2.6 to 8.1%) showed skin reactivity to latex. All latex-sensitive subjects reported glove-related urticaria, which was associated with rhinoconjunctivitis in 12 subjects and asthma in five subjects. No subject had a history suggestive of occupational asthma among those who had negative skin tests to latex. In the second part of the study, a histamine inhalation challenge was performed on 12 of 13 latex-sensitive subjects, including the five subjects with a history of occupational asthma. These 12 subjects demonstrated significant bronchial hyperresponsiveness. All underwent specific inhalation challenges with latex gloves in the laboratory. Seven subjects developed a significant bronchial response (four immediate and three dual reactions) to latex glove exposure. We conclude that occupational asthma due to latex occurred in 2.5% (95% CI: 1.0 to 5.2%) of hospital employees. Widespread use of latex gloves should therefore be considered a significant risk to the respiratory health of hospital employees.