This is protocol, stablished in the Hospital Nacional de Niños of Costa Rica Bood Bank, for emergency situations. We transfuse packed red blood cells (O positive) mixed with warm saline (0.9%), without blood type or cross match. This procedure reduce viscosity, the risk of ABO reactions and eliminate the posibility of clerical errors under emergency situations. We discusse the experience of the period since October 1993 to April 1994.