SummaryThe clinical and immunologic features often patients with allergic bronchopulmonary aspergillosis (ABPA), observed over periods varying from 12 months to 10 years, are reported.Acute attacks of ABPA were characterized by several, or all of: increased cough and sputum, haemoptysis, pleuritic pain, expectoration of sputum plugs, and increasing airways obstruction. Peripheral blood eosinophilia and acutely elevated serum IgE levels were seen in all patients during acute attacks, sputum eosinophilia and recovery ofAspergillusin sputum was less common. However, blood eosinophilia was not present in all attacks of ABPA and sputum eosinophilia varied similarly from one attack to another.Six patients with previously documented multiple precipitin lines have had no demonstrable precipitins toAspergilluson several occasions between attacks, three of these patients have also been negative during attacks. Five of the six patients have again developed positive precipitin lines.The total number of episodes in these ten patients was fifty two, three patients have had more than nine acute attacks of ABPA. There is no seasonal variation in this group of patients. Since diagnosis, only three patients have had an attack‐free interval longer than 12 months. Two patients are steroid‐dependent because of severe asthma, and nine have symptoms of bronchiecta