Background: Radical inguinal lymphadenectomy (ILND) for metastatic melanoma is associated with a high complication rate. Seroma is often the first postoperative complication, followed by prolonged wound healing sometimes requiring reoperation, infection, multiple outpatient visits and re-hospitalization. Prevention of seroma may, therefore, lead to a reduction in many of the other complications. Methods/design: The primary aim of this randomized study is to investigate whether fewer patients require treatment for seroma by immediate prophylactic application of incisional, Negative-pressure Wound Therapy (iNPWT) following ILND, compared to standard postoperative treatment. The secondary outcomes include surgical-site infection, dehiscence, hematoma, length of hospitalization, quality of life, safety, long-term assessment of lymphedema and non-inferiority oncological outcome. Data will be registered prospectively at check-ups after 7 and 14 days, 1 and 3 months and 2 years after inguinal lymphadenectomy using case report forms and questionnaires and stored in a secure online database. Discussion: To our knowledge, this trial is the first randomized study evaluating negative-pressure wound therapy as a prophylactic intervention for complications following melanoma-related ILND. The results from this trial will hopefully determine the efficacy and safety of prophylactic iNPWT treatment in prevention of the clinical relevant short- and long-term postoperative complications following ILND and may provide an evidence base for the an improved postoperative regimen.