This study involves research into the usefulness and safety of two probiotic products in maintaining remission in Crohn's disease and ulcerative colitis. Approximately 360 patients with Crohn's disease and ulcerative colitis from Ireland, Finland and Spain will be involved in the study. The yoghurts used in this study contain either Lactobacillus salivarius subsp. salivarius or Bifidobacterium infantis.