An experiment was conducted to determine the effects of caponization on the muscle composition, ATP-related compounds, the shear values, the taste panel scores and the muscle fiber areas of Taiwan country chicken cockerels. At 10 wks of age, cockerels were divided into two groups: caponized and untreated. Birds were fed grower and finisher diets ad libitum in an eighteen-week experimental period. Results showed that capons contained significantly greater muscle fat content, less breast and thigh muscle moisture content, shear value and muscle fiber area (p<0.05) than those of intact birds. However, neither treatment groups differed significantly (p>0.05) in breast and thigh muscle protein content. Compared with the intact birds, the capons contained significantly (p<0.05) less muscle ash content in the breasts, but did not differ significantly (p>0.05) in thigh muscle ash content. The breast muscle IMP and ATP+ADP+AMP+IMP contents in the intact birds were significantly (p<0.05) higher than those in the capons. The intact birds had significantly (p<0.05) higher ATP and AMP contents than did the capons as well as significantly (p<0.05) less ADP and inosine (HxR) contents in the thigh and breast muscles. The Hypoxanthine (Hx) content of the thighs in the intact birds was significantly (p<0.05) higher than that in the capons; however, there was an adverse effect on the breast muscle Hx content. The breast muscle K value in the intact birds was significantly (p<0.05) lower than that in the capons. The capons produced significantly (p<0.05) higher taste panel scores than did the intact birds for both flavor and juiciness of thigh muscle as well as for flavor and tenderness of breast muscle.