BACKGROUND AND PURPOSE: ustekinumab is a monoclonal antibody approved for the treatment of moderate to severe Crohn's disease (CD) and ulcerative colitis (UC). In spite of being an effective treatment, patients may have suboptimal response, or lose it over time. In these cases, ustekinumab intravenous (IV) maintenance therapy has been explored as a rescue option. METHODS: retrospective, monocentric, descriptive, observational study that included adult patients with inflammatory bowel disease who received maintenance therapy with intravenous ustekinumab after loss of response to intensified subcutaneous therapy. The primary outcome was a combination of clinical remission with biochemical and/or endoscopic response at week 12 after intravenous intensification. RESULTS: twenty-two patients were included and the primary outcome was achieved in 36.36 % of patients. At week 12, clinical remission was achieved in 40.91 % of patients, and biochemical remission in 63.64 %. The median Harvey-Bradshaw index (HBI) score in patients with CD decreased from 6 to 3 points at week 12 (p < 0.001), and to 2 points at week 52 (p = 0.004). After a median follow-up period of 31.46 months, 81.82 % of patients continued their treatment with ustekinumab. No adverse events were reported. CONCLUSIONS: maintenance therapy with intravenous ustekinumab seems to be effective and safe for the rescue of patients with CD and UC who lost response to intensified subcutaneous ustekinumab.