Background: Inguinal lymph node dissection (ILND) is associated with a high complication rate. Retrospective studies suggest that incisional negative pressure wound therapy (iNPWT) might reduce complications, especially seroma, following ILND. Methods: This was a prospective multicenter, randomized (1:1), open-labeled, parallel-group trial. Patients with macrometastic melanoma to the inguinal lymph nodes and eligible for ILND were randomized to receive either iNPWT for 14 postoperative days or conventional wound dressing. The primary outcome was seroma incidence. Secondary outcomes included surgical-site infection, wound rupture, wound necrosis, hematoma, rehospitalization and readmission rates between groups. All outcomes were registered 3 months after ILND and analyzed according to the intention-to-treat principle. Results: The trial was terminated early due to a low recruitment rate as a consequence of a change in the national treatment protocol, and the estimated sample size was not reached. Twenty patients were included and randomized in the study. The trial showed less seroma formation between the iNPWT 6/11 (55%) and control 7/9 (78%) groups; however, this was not statistically significant (p = 0.29). Similarly, there were no differences in the rates of surgical-site infection (p = 0.63), wound rupture (p = 0.19), wound necrosis (p = 0.82), hematoma (p = 0.19), reoperation (p = 0.82) or readmission (p = 0.34) between groups. Conclusion: There was a tendency toward fewer complications in the iNPWT group, however this trial was underpowered and could not confirm the hypothesis that iNPWT reduces complications after ILND. Future randomized controlled trials are required to fully evaluate the treatment potential of iNPWT. Trial registration: The trial was prospectively registered at https://clinicaltrials.gov/ct2/show/NCT03433937.