BACKGROUND: As extracorporeal shock wave therapy (ESWT) can enhance healing of skin graft donor sites, this study focused on shock wave effects in burn wounds. METHODS: A predefined cohort of 50 patients (6 with incomplete data or lost to follow-up) with acute second-degree burns from a larger study of 100 patients were randomly assigned between December 2006 and December 2007 to receive standard therapy (burn wound debridement/topical antiseptic therapy) with (n = 22) or without (n = 22) defocused ESWT (100 impulses/cm at 0.1 mJ/mm) applied once to the study burn, after debridement. Randomization sequence was computer-generated, and patients were blinded to treatment allocation. The primary endpoint, time to complete burn wound epithelialization, was determined by independent, blinded-observer. A worst case scenario was applied to the missing cases to rule out the impact of withdrawal bias. RESULTS: Patient characteristics across the 2 study groups were balanced (P > 0.05) except for older age (53 ± 17 vs. 38 ± 13 years, P = 0.002) in the ESWT group. Mean time to complete (≥95%) epithelialization (CE) for patients that did and did not undergo ESWT was 9.6 ± 1.7 and 12.5 ± 2.2 days, respectively (P < 0.0005). When age (continuous variable) and treatment group (binary) were examined in a linear regression model to control the baseline age imbalance, time to CE, age was not significant (P = 0.33) and treatment group retained significance (P < 0.0005). Statistical significance (P = 0.001) was retained when ESWT cases with missing follow-up were assigned the longest time to CE and when controls with missing follow-up were assigned the shortest time to CE. CONCLUSIONS: In this randomized phase II study, application of a single defocused shock wave treatment to the superficial second-degree burn wound after debridement/topical antiseptic therapy significantly accelerated epithelialization.