During the 2003-2005 military operations in Iraq, 32% of wounded soldiers were culture-positive for the multi-drug resistant Acinetobacter calcoaceticus-baumannii complex. Clinical infection occurred in 63% of these soldiers and included osteomyelitis, burn infection, and deep wound infection. Microbiology studies of chronic wounds demonstrate the existence of complex microbial ecosystems often involving more than one micro-organism (biofilms). The purpose of this study assessed the ability of a variety of silver-dressings to prevent biofilm formation by A. calcoaceticus and a mixed bacterial community representing an infected burn. In this study a microtitre plate model was used, which allows the biofilm to form on the surface of pegs. Test silver dressings were placed aseptically in the wells, followed by the addition of 200ƒÝl of bacterial culture (107 cfu/ml), with tryptone soya broth used for negative controls. The specialised lid was placed onto the microtitre plate, sealed with parafilm and incubated at 37„aC for 48h. Biofilm formation was assessed by staining with 1% crystal violet, measurement of optical density570nm. The data indicated that, nanocrystalline silver dressings prevented biofilm formation by A. calcoaceticus. However, strong biofilms were observed following incubation of with other silver dressings studied. Strong mixed burn flora biofilms were observed following incubation with dressings containing silver chloride, silver calcium phosphate or metallic silver. Biofilms represent a significant healthcare issue and there is growing evidence of their detrimental role in chronic infections, including those in wounds. Acinetobacter species are increasingly implicated in wound infection and osteomyelitis in active-duty military personnel. Rapid therapeutic intervention can be useful in preventing biofilm formation in wounds. Nanocrystalline silver dressings were shown to be the most effective at preventing biofilm formation by A. calcoaceticus and a complex mixed community using this in vitro assay.