Abstract. Solutions of stabilized 5 and 25% Normal Serum Albumin (Human) fractionated from plasma, placentas, and blends of these sources were subjected to repeated heatings for 120 h at 56 °C, interspersed with storage for 48 h at 4°C. Disc electrophoretic analyses showed that heating some solutions produced a reversible dimerization of the albumin related to the source, protein concentration, and number of heatings. Cellulose acetate electrophoresis showed that repeated heating produced a reduction in the amount of albumin with the formation of a component with a mobility slower than that of albumin. After eight heatings plasma albumin gelled; albumin from placental‐plasma blends partially gelled; there was no gelation of placental albumin after nine heatings.