In a prospective, randomised, controlled trial of 92 patients with full-thickness pressure ulcers, the efficacy of an alginate wound dressing was compared to that of an established local treatment with dextranomer paste. During treatment, a minimal 40% reduction in wound area was obtained in 74% of the patients in the alginate group and in 42% of those in the dextranomer group. The median time taken to achieve this goal was four weeks with alginate and more than eight weeks in the control group. Mean surface area reduction per week was 2.39cm2 (sd 3.54) and 0.27cm2 (sd 3.21) in the alginate and dextranomer groups respectively (p=0.0001). This difference was still highly significant when the sub-groups of almost completely healed subjects at the end of the study were considered. This striking healing efficacy of an alginate dressing suggests it possesses pharmacological properties which require further investigation.