The surface topography of different carbon black grades has been studied by STM. The high resolution of the method enables detailed images of the surface to be obtained. The activity of different grades has been attributed to the lateral dimensions of the graphitelike nanocrystalites acid their degree of orientation with respect to the surface. Fractal dimensions of the surface were obtained by the root-mean-square and the Richardson methods. The results are compared with fractal dimensions obtained by x-ray small angle scattering.