Introduction: Human mesenchymal stem cells (Prochymal brand of remestemcel-L) have been developed for experimental use in Crohn's disease and other conditions. Mesenchymal stems cells (MSCs) have been shown to inhibit inflammatory responses of innate and adaptive immune cells as well as have reparative effects on inflamed tissues. Promising preliminary therapeutic results of MSCs on gastrointestinal graft-versus-host disease have lead to Phase III trials for active Crohn's disease. Areas covered: This review examines the discovery and characterization of mesenchymal stem cells, their immune effects, their use in animal models of disease, the production and administration of remestemcel-L and the published results of trials of remestemcel-L and alternative MSCs in Crohn's disease. Expert opinion: The Prochymal brand of remestemcel-L represents the successful pharmaceutical development of mesenchymal stem cells for potential therapy in human disease. While preliminary results show promise of this therapy in terms of efficacy and safety, robust trials confirming efficacy results, explanation of the mechanism of response and estimates of effect compared to other biologics and immunosuppressants will be needed before this is an approved and widely accepted therapy. © 2011 Informa UK, Ltd.