The separation of rotting garden material from general domestic waste and its collection for processing in industrial composting sites is a relatively new industry in the UK. Two cases of allergic bronchopulmonary aspergillosis and the results of health surveillance are described in a team of 28 garden waste (compost) collectors. A few cases of extrinsic allergic alveolitis due to Aspergillus fumigatus have previously been reported in compost workers. In the absence of any guidance from research and to prevent similar cases of a potentially serious illness, we advise that new starters to the job of collecting or processing compost are screened for asthma and aspergillus sensitivity, cystic fibrosis, bronchiectasis and immunodeficiency if their exposure to high levels of Aspergillus sp cannot be controlled. Annual health surveillance for these workers is also recommended.