Recent studies have explored the role of the microbiota in disorders of gut-brain interaction, opening pathways for therapies, such as dietary adjustments, probiotics, and fecal microbiota transplantation (FMT). We present herein a pilot study on 4 patients with severe irritable bowel syndrome (IBS), refractory to conventional treatment, in which FMT through colonoscopy showed improvement in pain, bloating, and stool consistency that was maintained during the 6-month follow-up. To establish the broader clinical application of FMT, more research on its efficacy according to instillation site and patient results is needed. (c) 2025 Asociacion Mexicana de Gastroenterolog & imath;a. Published by Masson Doyma Mexico S.A. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/ by-nc-nd/4.0/).