BACKGROUND: Ankle sprains are usually treated with the RICE protocol often with nonsteroidal anti-inflammatory drugs (NSAID) for pain reduction. We evaluated the effect of diclofenac, an NSAID, versus paracematol in the reduction of pain and acute edema of severe ankle sprains.MATERIALS AND METHODS: Ninety patients, 18 to 60 years old, with Grade II acute ankle sprains were randomized into two groups. Group A (45 patients) received for the first 10 days diclofenac 75 mg orally twice per day. Group B (45 patients) received paracetamol 500 mg orally three times per day for the same period. We evaluated ankle joint edema with the Figure-of-Eight method and with the volumetric method, as well as pain with the Visual Analogue Scale (VAS) in both groups.RESULTS: The patients had no significant differences concerning their baseline values (p > 0.05). The ankle joint edema was decreased in both groups (p < 0.001) but there was more edema in group A than in group B at the third post-traumatic day with both measurement methods (p = 0.028/0.025). By the tenth post-traumatic day no difference was found. Pain decreased in both groups at the third day and at the tenth day (p < 0.001).CONCLUSION: According to these results, diclofenac and paracetamol had the same effect on pain reduction of ankle sprains but more acute ankle edema was present in patients who were treated with diclofenac than in patients who were treated with paracetamol.