Objective To establish a monkey model of muscle atrophy by fixing the right lower limb and set up e-valuation criteria for that model. Methods Twelve healthy,6-7 year old male cynomolgus monkeys(body weight 6-7 kg)were used in this study. All animals were normal and had no malformed lower limb bones. Right lower limbs of the an-imals were fixed with fiberglass bandage(from knee joint to anklebone)for 15 weeks. Body weight,crus perimeter and crus volume were recorded every two weeks. MRI examinations of the gastrocnemius muscle were conducted at weeks 11,13 and 15. Muscle biopsy was taken for pathological examination at week 15. Results There were no obvious changes of body weight during the experiment. At 15 weeks after modeling,the right crus perimeter and crus volume of the experimental an-imals were significantly decreased(P <0.05),and some biochemical indexes such as serum creatinine,gloucose and al-kaline phosphatase were significantly decreased(P <0.05), while cholesterol was significantly increased(P <0.05).MRI showed atrophy of the right gastrocnemius muscle. Muscle biopsy also showed muscle atrophy and muscle fibers be-came thinner in the right gastrocnemius,and the cross-section area of the muscle fibers was significantly decreased. Con?clusions It is easy to operate and establish a muscle atrophy model in Cynomolgus monkeys by fixing the right lower limb. This model is suitable for objective and easy evaluation of muscle atrophy by measurement of crus perimeter and crus volume of the limb,blood biochemical parameters,MRI examination,and histopathological examination in combination.