Inflammatory bowel disease (IBD) has become an increasingly frequent chronic health problem in the last few decades, particularly in developing countries. In young adults, one of the most common forms of IBD is Crohn's disease (CD). CD is a multifactorial genetic disease characterized by a transmural granulomatous inflammation that especially affects the terminal ileum and the colon. As it involves defective inflammatory pathways, the immune adaptive complex, and environmental factors, this disease has periods of remission and recurrence followed by diarrhea, abdominal pain, and malnutrition, which often lead to lumen bowel stenosis associated to multiple fistulas. In addition, the growth of mesenteric adipose tissue (MAT) near the affected intestinal area is a hallmark of CD. Evidence linking the development of mesenteric and intestinal alterations in CD is increasing. The aim of this chapter is to address adipose tissue in general, the morphological and functional differences between its compartments, the main characteristics of MAT in CD, and its possible role in the etiopathology of this immune-mediated disease.