Inflammatory Bowel Disease (IBD) is a chronic disease which emerges mainly in young patients, affecting quality of life, frequently it is a progressive disease and it generates high medical costs. Two principal types of IBD, Crohn’s disease and ulcerative colitis share many characteristics. Although the etiology is still unclear, it is known that is a multifactorial disease characterized by immune response to the gut microbiota in genetically susceptible individuals. Clinical manifestation is highly variable, so there are different phenotypic subtypes and a different evolution and prognostic. In order to contribute to improve the knowledge about the etiology of IBD, and to improve the diagnosis and clinical prediction of the patients, LIGHD studies and classifies the immune response of the patients at cellular level and studies new genetic contributions in IBD patients. This research line lies within the framework of precision medicine for IBD patients in order to improve the knowledge of the etiology, their diagnosis, to contribute to clinical prediction of the pathology and to optimize their treatments.