Discussed in this paper are (1) the technique of removing thin layers of silicon by the anodic oxidation method; (2) the measurement of the sheet conductance of diffused layers in silicon by the four-point probe method; and (3) the measurement of impurity distribution of diffused layers in silicon by the four-point probe and the anodic oxidation technique.Emphasis has been given to the practical aspects of the experimental techniques including the precautions to be taken to achieve uniform and thin (300-1500?) layer removals from the silicon surface by the anodic oxidation method; the methods to control and to check the thickness of the layer removal; the errors introduced in the sheet conductivity and in the impurity distribution measurements respectively; and the steps to be taken for error reduction.For illustration, a typical example is given for the measurement of the impurity distribution of phosphorus diffusion into silicon. The diffusion depth is 4.9 /μm. Spacings between measurement points range from 400? to 1600?. The error for sheet conductivity measurement is estimated to be less than 3%, that for impurity distribution is estimated to be less than 20%. Problems that remain to be solved are briefly mentioned.