Objectives This study aimed to evaluate the influence of fungal infection and antifungal treatment on outcome in patients with walled-off pancreatic necrosis (WON). Methods A retrospective description of fungal infections in a cohort of consecutive patients undergoing endoscopic, transmural drainage and necrosectomy for WON, treated in a tertiary referral center was reviewed. Results Between 2005 and 2013, fungal infection in WON was documented in 57 (46%) of 123 patients. The most common isolates at first positive culture were Candida albicans (55%) and Candida glabrata (20%). Thirty-nine (70%) patients were treated with antifungals after the first fungal finding. There was no significant difference in mortality (21% vs 13%, P = 0.517) or organ failure (34% vs 33%, P = 0.903) between the group treated with adequate antifungals after the first fungal finding compared to the group not treated or treated inadequately. The in-hospital mortality was 18% (10 patients). Concomitant fungemia was found in 6 patients, of which 3 died, as opposed to 7 with fungi in the necrosis only (50% vs 14%, P = 0.027). Conclusions This study demonstrates a high incidence and associated high in-hospital mortality of fungal infection in WON, thus emphasizing the importance of fungal infections in WON.