Disc electrophoreses of human sera from 180 patients with various diseases were carried out, and the changes of electrophoretic patterns and the relative concentrations of the protein fractions were studied in comparison with those of 52 normal subjects reported in the previous paper (26).1) In liver diseases, other than obstructive jaundice and cholecystitis, the number of protein fractions decreased and γ-globulin increased and showed two peaks in many cases. The haptoglobin bands were reduced in intensity especially in parenchymatous disorders of the liver. In obstructive jaundice and cholecystitis electrophoretic patterns were similar to those of normal subjects except that the haptoglobin zones appeared more clearly; prealbumin, albumin, αL, α1', α2', Fα2, and β2' decreased, and βγ, Sα2 and Sβ increased. Transferrin decreased markedly in severe acute hepatitis, Banti's syndrome, Wilson's disease and hemochromatosis.2) In renal diseases the characteristics of the electrophoretic patterns were that the haptoglobins appeared distinct and γ-globulin became decreased, whereas the number of protein fractions of sera from patients with renal diseases was not less than that of normal subject. Usually albumin decreased, and βγ, Sα2 and Sβ increased. Transferrin and αL increased markedly in nephrotic syndrome3) In the patients with gastric cancer and peritonitis carcinomatosa three groups of sera could be distinguished: 1. Sera with electrophoretic patterns similar to those of normal, 2. sera with decreased haptoglobin bands, and 3. sera with increased haptoglobin bands. In leukemia the patterns showed many distinct haptoglobin bands and faint γ-globulin zone. Postalbumin (σ) was seen in many cases of malignant tumors, prealbumin and albumin decreased, βγ, Sα2 and Sβ increased. Transferrin decreased markedly in sera from patients with gastric cancer and peritonitis carcinomatosa.4) In inflammatory diseases, rheumatic fever, and rheumatic arthritis, haptoglobins increased.