The effects of three final filter pore sizes on sepsis and survival times in rabbits infused with contaiminated intravenous fluids were compared. Intravenous fluids were administered for up to 12 hours to five groups of rabbits. Groups 2, 3 and 4 received fluids, contaminated with Gram-negative rods, that were filtered with 0.22-, 1.0- and 5.0-micrometers filters, respectively. Rabbits in Groups 1 and 5 received uncontaminated and contaminated fluids, respectively, neither of which was filtered. Cultures were taken of blood and of fluid below the filters, and rabbit survival times were recorded. At 6, 8 and 12 hours, Group 2 survival time was not significantly different from that of the negative control; the survival times for Groups 3, 4 and 5 were significantly less than for the negative control. Fluid and blood cultures of Group 2 were negative or statistically indistinguishable from those of Group 1. Cultures for Groups 3, 4 and 5 were positive. The study suggests that 1.0- and 5.0-micrometers inline final filters have no beneficial effect on survival following infusion of contaminated fluids, but that 0.22-micrometer inline final filters increase survival time.