Five fungi including Aspergillus niger, Penicilium pinophilum, Chaetoomium globsum, Gliocladium virens and Aureobasium pullulans were used to investigate the biodegradation of starch-based elastomers: polyethyleneoctene elastomer (POE)/starch and grafted POE-g-MAH/starch copolymer blends. The viability of the composite spore suspensions were measured before estimating the fungal growth on the surface of specimens. The weight loss, morphology and mechanical properties of the blended specimens were measured using scanning electron microscopy and a mechanical properties tester after 28 days of culturing. The spore suspension in the experiment showed good viability. Pure POE and POE-g-MAH did not allow significant fungal growth. Pure POE did not lose weight or have a change in tensile strength, but pure POE-g-MAH lost about 0.07% of its weight with a slight reduction in tensile strength during culture period. There was heavy growth on the surface of POE/starch and POE-g-MAH/starch blends after 28 days of culturing. The weight loss of POE/starch and POE-g-MAH/starch blends increased with increasing starch content. POE-g-MAH/starch blends tended to lose more weight than POE/starch blends. After biodegradation, the surface of POE/starch and POE-g-MAH/starch blends became rough with many holes and cracks, indicating that the films were eroded by the fungi. Tensile strength of POE/starch and POE-g-MAH /starch blends decreased after culturing because of microbial attack. On the contrary, elongation at break of POE-g-MAH/starch blends increased after biodegradation. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 3574-3584, 2009