Introduction: This study aimed to assess the analgesic efficacy of oxycodone at doses of 10 mg and 20 mg in dressings after surgery of burn wounds. Material and Methods: Twenty adult patients who underwent surgical treatment of third-degree burn wounds under general anaesthesia were included. Burn wounds were treated with dressings, to which oxycodone was added at 20 mg in Group 1 and 10 mg in Group 2. After the surgery, plasma oxycodone and noroxycodone concentrations were assayed, and pain intensity was assessed with Numerical Rating Scale (NRS). Results: In Group 1, no patient reported pain; in Group 2, four patients reported pain. The pain intensity, according to NRS, was 1–8. Plasma concentration of oxycodone in the blood serum was in the range of 1.24–3.15 ng/mL and 1.09–1.28 ng/mL in Group 1 and Group 2, respectively. Noroxycodone was not detected in the plasma. Adverse effects were not observed in any of the treated patients. Conclusions: Oxycodone in dressings provides patients with adequate and safe analgesia.