This study was conducted to compare the development and histochemistry of pectoralis and iliotibialis lateralis muscles between different raising systems of ducks; free ranged in paddy fields and housed, and among three types of breeds; Crossbred (Mallard×Khaki Cambell), Indian Runner and Chinese native. Three birds of both sexes from each breed at the age of 12 days were introduced into the paddy field (4a) at the first week after rice planted, kept for 72 days, and then transported into the pen where the birds were fed with formula diet for layers. The rest of the birds were fed with the same formula diet from the beginning of the experiment in the pen (1.9a). All the birds were killed at 21 weeks of age. The results obtained were follows;<br>1. Body weight and the weights of pectoralis and iliotibialis muscles did not show any differences between free ranged and housed ducks, but breed differences were observed. Body weight was the greatest in Chinese native, and followed by Indian Runner and Crossbred (Mallard×Ckhaki Cambell). The pectoralis muscle was most developed in Crossbred (Mallard×Khaki Cambell), and the iliotibialis lateralis muscle was in Indian Runner.<br>2. Both the muscles were composed of only type II fibers with a high contraction speed. Type II fibers were subdivided into two types;1) type II A fibers with high oxidative enzyme activity, 2) type II B fibers with low oxidative activity. Thepectoralis muscle was composed of around 70% type II A fibers and 30% type II B fibers. The iliotibialis lateralis muscle was composed of around 40% type II A fibers and 60% type II B fibers. The housed Chinese native had more type II A fibers and less type II B fibers in the iliotibialis lateralis muscle than the free ranged. Among the breeds, Crossbred (Mallard×Khaki Cambell) possessed the highest percentage of type II A fibers, and the lowest of type II B fibers in the pectoralis muscle. Indian Runner had the highest percentage of type II A fibers, and the lowest of type II B fibers in the iliotibialis lateralis muscle.<br>3. The muscle fiber diameter was smaller in type II A fiber than type II B fibers in both the muscles. In comparison among the breeds, Crossbred (Mallard×Khaki Cambell) and Indian Runner had a larger diameter of type II B fibers in the pectoralis muscle. In the iliotibialis lateralis muscle, Indian Runner and Chinese native had a larger diameter of both type II A and II B fibers.<br>4. These results suggest that the effects of the different raising systems on muscle development of ducks were a little, and a higher flying ability in Crossbred (Mallard×XKhaki Cambell), running or walking ability on the ground in Indian Runner and meat productivity in Chinese native ducks.