Microbiological samples were taken from deteriorated oil paintings exhibited in various locations in addition to private possessions. The results showed that eight fungal and four bacterial species were isolated from these objects. These isolates were studied to measure their ability in degrading cellulose, gelatin, linseed oil and the varnish dammar. They were also tested for their potentiality to produce extracellular cellulases and proteases enzymes. The effect of different concentrations of benlate, coside 101 and some natural oils such as cloves, jojoba and garlic oils on the radial growth of the tested fungi and bacteria was studied. The results showed that all the tested biocides had a negative effect on the growth of the tested isolates and a single biocide is sufficient to kill a number of fungal species effectively. Key words: oil painting, biodeterioration, fungi, bacteria, cellulases, proteases, natural oils.