Rates of comorbidity are higher in patients with eating disorders and also the number of comorbid disorders is numerous. Most comorbidities associated with eating disorders are mood disorders, anxiety disorders, personality disorders, and substance use disorders. According to past research, there is a high rate of comorbidity of alcohol-substance abuse and eating disorders. Although the majority of studies in this area are focused on the use of alcohol, studies that have identified an association between illegal substance use and eating disorders are also available. In a study in the USA, the use of cannabis with anorexia nervosa (AN) and bulimia nervosa (BN) disorders is reported to be 6-7%. In Turkey, in a study that investigated the comorbidity of eating disorders and substance use, the use of alcohol and cannabis was reported in cases of BN, but the use of psychoactive substances and cannabis was not established in cases of AN. Among eating disorders, alcohol or drug abuse are most often found in individuals with bulimia nervosa and bulimic behaviors. Also, binge eating/purging anorexics appear to be more likely than restricting anorexics to indulge in substance use. Patients with bulimia nervosa have significantly higher rates of use of amphetamines, barbiturates, marijuana, tranquilizers, and cocaine than patients with anorexia nervosa. Compounds of cannabis like tetrahydrocannabinol activate endogenous cannabinoid receptors (CB1 and CB2) in brain. Stimulating the CB1 receptor is known to cause increased appetite and an antiemetic effect and because of these effects cannabinoids are included in clinical use. In this case report, an anorexia nervosa case, who was a young female patient using cannabis, will be presented. The patient, a 17 year-old, high school student, lived with her family, had complaints of weight loss and had used cannabis for three years. Before beginning to use cannabis her BMI was approximately 22, when referred to our clinic it was 15.6. She indicated that at first cannabis caused increased appetite, but excessive vomiting occurred in the first few months and then she started to exercise excessively. Although she noticed losing weight in this way, she did not stop the use of cannabis. According to a review of the literature in Turkey, such a case of cannabis use and anorexia nervosa comorbidity hasn't previously been reported. In this respect, discussion of the case in detail is important.