This study was carried out to examine the histochemical properties of muscle fiber in Korean Native chickens(KNC). Wangchoo(crossbred) and broiler were used as controls in this study. Live weight and the weight of the pectoralis profundus and iliofibularis muscles differed greatly among breeds. The largest live weight and muscle weight were obtained in broiler, the next in crossbred and the smallest in KNC. In percentage distribution of each fiber type, based on the reactivities for myosin adenosine triphosphatase and reduced nicotinamide adenine dinucleotide dehydrogenase., the pectomlis profundus muscle was composed only of type IIW fibers throughout the experimental period in all breeds. However, the iliofibularis muscle was composed of type IR, IIR and IIW fibers. In the iliofibularis muscle, the highest frequency of type IIR fibers occured in the breeds, and type IR was the lowest percentage. In the same fiber type, the activities of reduced nicotinamide adenine dinucleotide dehydrogense were different among the breeds. When KNC was compared with the crossbred, it showed higher frequency of type IIR fibers and lower frequency of type IIW fibers. The percentage of type IIR fibers of the female was higher than that of the male. The largest diameter of fiber was measured in broiler and the smallest in KNC, and the male had larger diameter than the female. A breed with larger body weight or iliofibularis muscle weight was exhibited larger diameter in each fiber type compared to the other breeds. At 7 weeks age, the largest diameter was measured in type IIt of crossbred, but diameter of type IIW was the largest in KNC. Broiler was the largest in the diameter of type IIW fibers at 7 weeks age, but the crossbred and KNC was the largest in the diameter of type IR fibers at 15 weeks age.