Ileal pouch-anal anastomosis (IPAA) is an effective surgical alternative to a permanent ileostomy following proctocolectomy in patients with ulcerative colitis (UC). Anastomotic leakage (AL) is a serious postoperative complication of an intestinal anastomosis that is associated with increased morbidity and mortality. The aim of this study was to evaluate the longitudinal long-term functional outcomes of patients who had IPAA that was complicated by AL. A retrospective longitudinal cohort study was performed of patients who had an IPAA procedure at a tertiary referral centre and a metropolitan private centre in Australia, over a 14-year period (October 2003-October 2017). The long-term functional outcome was assessed using objective clinical measures such as the number of bowel motions during the day and overnight, ability to defer defaecation and the presence of faecal incontinence, and repeated at annual intervals. A total of 138 patients [mean age 38.5 (± 16.9) years, 72 males] satisfied the inclusion criteria. AL was diagnosed in 14 (10%) patients [mean age 38.8 (± 17) years, 10 males], 11 (79%) of which were managed with surgery. The median bowel motion frequency during the day and overnight remained stable over a median of 62 (28-91) months follow-up, with no significant difference between those who had AL or not (p = 0.6, p = 0.1 respectively). The incidence of faecal incontinence remained low, and the majority of patients in both groups were able to defer defaecation for more than 60min. Six patients (4.3%) had their pouch excised. There is no statistical difference in longitudinal function between patients who experienced AL after IPAA surgery for UC compared with those who did not. Therefore, an acute AL does not negatively impact long-term functional outcomes in IPAA patients.