OBJECTIVE: Chronic foot ulcers are a common, severe, and expensive complication threatening life and limb in patients with diabetes. The aim of the present study was to investigate the effect of dalteparin on ulcer outcome in patients with diabetes, peripheral arterial occlusive disease, and chronic foot ulcers. RESEARCH DESIGN AND METHODS: A total of 87 patients were investigated in a prospective, randomized, double-blind, placebo-controlled trial. Participants were randomized to treatment with subcutaneous injection of 5000 units dalteparin (Fragmin, Pharmacia Corporation; n = 44) or an equivalent volume of physiological saline (n = 43) once daily until ulcer healing or for a maximum of 6 months. Ulcer outcome was investigated by evaluating the number of patients 1). who healed with intact skin; 2). in whom the study ulcer was improved, unchanged, or impaired; or 3). who were amputated above or below the ankle level, as compared with control subjects. RESULTS: Two patients, one on dalteparin and one on placebo, dropped out of the study. Ulcer outcome was significantly better (P = 0.042, two-sided chi(2) test for trend) in the dalteparin group (n = 43) compared with the placebo group (n = 42). A total of 29 patients healed with intact skin (n = 14) or decreased the ulcer area >or=50% (n = 15) in the dalteparin group compared with 20 (n = 9 and 11, respectively) in the placebo group. Five patients in each group showed impaired ulcer healing, i.e., the ulcer area increased >or=50%. Two patients in the dalteparin group were amputated compared with eight in the placebo group. Time to healing with intact skin was 17 +/- 8 weeks in the dalteparin group compared with 16 +/- 7 weeks in placebo group (NS). CONCLUSIONS: The results of the present study indicate that dalteparin improves the outcome of chronic foot ulcers in diabetic patients with peripheral arterial occlusive disease.