Mandelbrot' s fractal theory regards that many natural and medical images as the end result of Fractional Brownian Motion(FBM) . The fractal dimension is suit to measure the fineness or roughness of the surface.Based on this idea

the fractal dimension is applied in classifing ultrasonic images of muscle organ in this article. After the fractal dimensions of 60 sam- ples are calculated by this way

then classified by Bayes classifier

the correct classification rate accounts to 88.33%。The very high rate provethat the fractal dimension can be a new feature for clinical diagnose and very significant to improve the correct diagnostic rate.