Respiratory symptoms developed in 5 patients who were exposed to chloramine-T, a potent disinfectant used in cleaning butcheries, kitchens, and operating theaters. Skin tests, performed in 4 patients, showed an immediate type of wheal and flare reaction followed by a late-type infiltrative reaction. In 3 patients, inhalation tests with chloramine-T were done. 1 patient showed asthmatic bronchial obstruction, immediately after inhalation, followed by a late-type asthmatic reaction after some hours. 2 patients only exhibited late-type reactions, 4-8 h after challenge. The late bronchial response lasted for several hours or even days and was accompanied by leukocytosis in all 3 patients and a slight fever in 1 patient. No evidence of alveolar involvement appeared. Pre-challenge inhalation of cromoglycate in 1 patient ameliorated the late response considerably.