Porcine full-thickness excisional wounds were treated with 4 different hydrocolloid (HCD) dressings--DuoDERM (ConvaTec/E. R. Squibb), Intrasite HCD (Smith and Nephew Medical), Tegasorb (3M) and Replicare (Smith and Nephew Medical). Animals were killed at 4, 10, 21 and 90 d post-wound, excision sites were fixed in formalin and processed for histological analysis. Granulomatous lesions were observed following treatment with each of the 4 HCD dressings. Such lesions developed between 4 and 10 d post-wound, exhibiting little evidence of resolution at 90 d post-wound. Of the 4 dressings examined, DuoDERM and Intrasite HCD precipitated the most severe reaction, each treatment resulting in granulomata with a distinct and different morphology. Treatment with DuoDERM resulted in granulomata characterised by a random distribution of dendritic cells, epithelioid cells, multinucleated giant cells, lymphocytes and plasma cells. In contrast, treatment with Intrasite HCD resulted in highly organised granulomata, consisting of a central focus of epithelioid cells surrounded by a peripheral cuff of macrophages, lymphocytes and plasma cells. This experimental study highlights chronic inflammatory lesions that may, if reflected in the clinical environment, question the efficacy and indication of HCD dressings in the treatment of wounds having a number of different aetiologies.