The effects of the starch content, photosensitizer content, and compatibilizer on the photobiodegradability of low-density polyethylene (LDPE) and banana starch polymer blend films were investigated. The compatibilizer and photosensitizer used in the films were PE-graft-maleic anhydride (PE-g-MA) and benzophenone, respectively. Dried banana starch at 0-20% (w/w) of LDPE, benzophenone at 0-1% (w/w) of LDPE, and PE-g-MA at 10%, (w/w) of banana starch were added to LDPE. The photodegradation of the blend films was performed with outdoor exposure. The progress of the photodegradation was followed by determining the carbonyl index derived from Fourier transform IR measurements and the changes in tensile properties. Biodegradation of the blend films was investigated by a soil burial test. The biodegradation process was followed by measuring the changes in the physical appearance, weight loss, and tensile properties of the films. The results showed that both photo- and biodegradation rates increased with increasing amounts of banana starch, whereas the tensile properties of the films decreased. The blends with higher amounts of benzophenone showed higher rates of photodegradation, although their biodegradation rates were reduced with an increase in benzophenone content. The addition of PE-g-MA into polymer blends led to in increase in the tensile properties whereas the photobiodegradation was slightly decreased compared to the films without PE-g-MA. (c) 2006 Wiley Periodicals, Inc.