An outbreak of occupational diseases involving 38 metal workers with local infections on the hands and the face (53%), bronchitis (29%), and bronchopneumonia (18%) urged an examination of 150 samples of emulsions which the workers used in processing metals. Among the isolated bacteria, the most frequent was Pseudomonas aeruginosa (48%), followed by Escherichia coli (44%), Proteus spp. (11%), Enterococcus faecalis (9%), Enterobacter aerogenes (7%), Citrobacter spp. (5%), Shigella spp., Staphylococcus aureus (3%), and the sulphite reducing Clostridia (1%). Moulds and yeasts were isolated from all tested samples. Most samples counted about 3 x 10(5)/ml of colony forming units. It was concluded that all emulsions and other substances which come in direct contact with the workers should be regularly monitored. Furthermore, preservatives should be added to prevent microbial infection.