OBJECTIVES To compare the efficacy of a sequential strategy combining calcium alginate and hydrocolloid dressings treatment of grade III or IV pressure ulcers (PUs) and the efficacy of nonsequential strategy with hydrocolloids alone. DESIGN An open, randomized, multicenter parallel-group trial. SETTING Twenty geriatrics hospital wards. PARTICIPANTS One hundred ten older patients with grade III or IV PUs. INTERVENTION The control strategy consisted of applying hydrocolloid dressings (DuodermE) for 8 weeks; the sequential strategy consisted of applying combined calcium alginate dressings (UrgoSorb) for the first 4 weeks and hydrocolloid dressings (Algoplaque) for the next 4 weeks. MEASUREMENTS PU surface areas were measured weekly by ulcer tracing. The endpoints were the mean absolute surface area reduction (SAR) during the 8-week study period and the number of patients achieving a 40 or more SAR (SAR40). RESULTS Fifty-seven and 53 patients were randomly allocated to sequential and control strategies respectively. Baseline patient characteristics and PU ulcer features at inclusion were similar in the two groups. Mean +/- standard deviation SAR was significantly larger in the sequential treatment group (5.4 +/- 5.7 cm2 and 7.6 +/- 7.1 cm2 at 4 and 8 weeks) than in the control group (1.6 +/- 4.9 cm2 and 3.1 +/- 7.2 cm2, P< .001). In the sequential treatment group, 68.4 of the patients reached SAR40 at 4 weeks and 75.4 at 8 weeks, proportions significantly larger than in the control group (22.6 and 58.5, respectively, P< .0001). Dressing tolerance was good in both strategies. CONCLUSIONS In grade III or IV PUs, treatment using first calcium alginate dressings and then hydrocolloid dressings promotes faster healing than treatment with hydrocolloid dressings alone.