Hevein is a small cystine-rich protein with a polypeptide chain length of 43 residues. It occurs in the lutoid body fraction of rubber latex, has affinity for chitin, and inhibits fungal growth. It was isolated from the effluent of a rubber factory in a yield of about 0.7 g/l. The elution position of the protein on reversed-phase HPLC, analysis by ion-spray mass spectrometry and its one-dimensional NMR spectrum indicated that it was identical to the protein isolated from the lutoid-body fraction. The total amount of other proteins in the effluent from the rubber production was less than 0.2 g/l. This means that the effluent of rubber factories is a very suitable source for the isolation of a protein that presumably has antifungal properties.