During the last decade an increasing number of plants for reuse of refuse have been constructed in Europe and USA. During the same period several cases of occupational respiratory diseases among workers in the recycling industry have been reported. In an earlier study we have showed that isolated basophile from pig-farmers with asthma were sensitized against pig-protein. The aim with this study was to show if there was some individual differences by histamine release from basophile leucocytes. Nine formerly compost workers and five earlier unexposed persons have been examined. The histamine release was studied in isolated basophile leucocytes after incubation with suspensions of 35 days old compost and Aspergillus fumigatus. Compost caused histamine release from basophile leucocytes from both formerly compost workers and control persons. However, Aspergillus fumigatus caused histamine release in 3 of the workers and none of the control persons.