Blend films of poly(3-hydroxybutyric acid) (PHB) with chitosan were prepared, and their Physical properties and crystallization were investigated. The degree of crystallinity of PHB/chitosan films by X-ray diffraction decreased with increasing chitosan concentration. In the fourier-transformed infrared spectra, carbonyl peak of PHB became lower with increasing the amount of chitosan. The addition of chitosan to PHB film decreased thermal stability and crystallinity of the blend films. The granular sizes of the films were reduced with the addition of chitosan to the film in the microstructural observation by a scanning electron microscope. Mechanical properties, including tensile strength and percent elongation, of the blend films increased with increasing chitosan ratio in the films. For color of the films, L and b values generally decreased with increasing chitosan ratio, but transparency of the films increased.