Three different techniques of lead adminitration-per os, subcutaneous injection, and inhalation-were used in rabbits to study serum protein fractions by paper-electrophoresis. The paper-electrophoresis was carried out with technical precaution by which physiochemical conditions required for the electrophoretic procedure were satisfied, as pointed out by one of the authors (Y.H.) in a recent paper. A precision exposing chamber equipped with the Wright's dust feed mechanism (British made) was designed for long-term inhalation. The results obtained are as follows: 1) γ-globulin level was elevated in the course of the experiment in cases using the last two techniques. In the case using the oral method, no change was found. 2) α2-globulin level was slightly increased in cases using any of the three techniques. 3) Albumin level was significantly decreased in all the three sets of cases, especially in those by inhalation method. 4) It was noted that the fractional value of serum proteins might be affected by ingredients of foods, i.e. the commercial rabbit chow and the ordinarly fresh green.