Two cases of bisalbuminaemia are hereby studied: a congenital case and an acquired or transitory case. In the first one, this hereditary disturbance is studied on four affected members of one Spanish family, being associated in two of them with multiple lipomatosis. This kind of association is considered as casual. As in most of the informed cases, ours belongs to the slow kind. The second case deals with a bisalbuminaemia of transitory character or pseudobisalbuminaemia which, appeared in a woman in the course of an acute pancreatitis of biliolithiasic origin, with a pancreatic pseudocyst and pleural effusion, the evolution in the inflamatory pancreatic process being advantageous in spite of the prsence of bisalbuminaemia. Briefly revised, are exposed the causes of this interesting and rare alteration in the electrophoretic fractioning of plasmatic proteins: congenital, and adquired causes due to administration of betalactamines and during the course of acute pancreatitis.