Reconstituted recombinant factor VIII (FVIIIrec) loses little biologic activity at room temperature for up to seven days and continuous infusion is convenient, effective hemostatically and requires less FVIIIrecconcentrate than treatment by conventional bolus injections. However, the potential for bacterial contamination, with proliferation to high levels that can cause bacteremia, is a concern with continuous infusion. We studied the growth properties at 4, 25 and 35°C in reconstituted FVIIIrec(Kogenate®) and at 25°C in 5% dextrose in water (D5%W) of three isolates each ofStaphylococcus epidermidis, Staphylococcus aureus, Enterobacter cloacae, Klebsiella oxytoca, Serratia marcescens, Acinetobacter calcoaceticus, Stenotrophomonas maltophilia, Pseudomonas aeruginosa, Burkholderia cepacia,Flavobacterium spp. andCandida albicans, species most likely to contaminate infusate during preparation or administration and which have been implicated in more than 95% of all outbreaks and sporadic cases of nosocomial bloodstream infection traced to contaminated admixtures, biologic agents or medications administered parenterally. Reconstituted FVIIIrecallowed growth of only three species at 25°C and 35°C:S. marcescens, S. maltophiliaandP. aeruginosa; logarithmic growth appeared only after 24–48 h. D5%W allowed growth of two gram-negative species,S. marcescensandB. cepacia.We conclude that reconstituted FVIIIrec(Kogenate®) is a poor growth medium for most nosocomial pathogens, comparable with D5%W. If reconstituted aseptically, continuous infusion of reconstituted FVIIIrecshould be safe, and it should not be necessary to replace the container or tubing more frequently than every 3 days, an administration schedule that can provide effective hemostasis at lower cost.