The studies reported here have been undertaken to assess the potential use of isothermal microcalorimetry in studying the antimicrobial efficacy of wound dressings that contain antimicrobial agents. The microcalorimetric technique allows non-invasive and non-destructive analysis to be performed directly on a test sample, regardless of whether it is homogeneous or heterogeneous in nature. Microcalorimetry is an established procedure that offers quantitative measurements and has the distinct advantage over traditional antimicrobial test methodologies in that calorimetric measurements are made continuously over real-time, thus the dynamic response of microorganisms to an antimicrobial agent is observed in situ. The results described in this paper are for interaction of two silver-containing wound care products AQUACEL Ag Hydrofiber (ConvaTec, Deeside, UK) and Acticoat 7 with SILCRYST (Smith and Nephew Healthcare, UK) with the wound pathogenic organisms Staphylococcus aureus and Pseudomonas aeruginosa. Both dressings are shown, microcalorimetrically, to have the capacity to kill these common wound pathogens within 1-2 h of contact. A dose-response study was conducted with the AQUACEL Ag dressing. Microcalorimetry is shown to be rapid, simple and effective in the study of the antimicrobial properties of gel forming wound dressings.