The registered dietitian is an essential member of the treatment team for assessment and rehabilitation of nutrition needs, for development of patient treatment plans, and for planning healthy life-styles. Attention to food and nutrition intake behaviors will aid the overall goal of quality sobriety and relapse prevention. Nutrition, which includes physiological and psychosocial disciplines, is involved in every aspect of recovery. It is imperative that a qualified nutrition professional be a part of each individual's recovery and foundation for relapse prevention. Many debilitating nutritional consequences result from drug and alcohol abuse. Chronic nutrition impairment causes serious damage to the liver and brain, which reinforces the craving for more drugs and alcohol and perpetuates the psychological aspect of addiction. During treatment, efforts are concentrated on the physical recovery, providing adequate nutrition to replete and heal the brain, liver, and digestive system. Nutrition makes a difference in the rate and quality of physical recovery, which prepares individuals to function at a higher level in treatment--cognitively, mentally, and socially. Improved nutritional status can make treatment more effective, while reducing drug and alcohol craving, thereby preventing relapse. Nutrition professionals should take aggressive action to ensure involvement in treatment and recovery programs. In addition, they are encouraged to participate in nutrition research activities to strengthen the knowledge base in this area.