In patients with Crohn's Disease (CD), malnutrition is frequently observed and is an important complication, frequently associated with nutritional deficiencies, especially vitamins (both water- and fat-soluble) and essential trace elements. It is often a result of the disease activity, poor oral intake and/or restrictive diets. Nutrition plays an important role in disease management and helps to maintain remission in CD patients. Deficiencies occur in patients with active Crohn's disease, and also in those in remission. Specific supplementation of vitamins and micro- and macronutrients might be helpful or even necessary in this group of patients. This review outlines the most frequent nutritional deficiencies and their complications in relation to the Crohn's Disease Activity Index, and provides an overview of therapeutic perspectives for CD patients in adult patients with inflammatory bowel disease (IBD). Biological therapy, which is being used with increasing frequency, seems not only to mitigate the inflammatory process in the gastrointestinal tract, but also has significant impact on the nutritional status of patients with Crohn's disease.