Eating disorders are characterized by severe disturbance in eating behavior. A disturbance in perception of body shape and weight is an essential feature of both anorexia nervosa (AN) and bulimia nervosa (BN). Eating disorder patients demonstrate the same characteristic attitude about body image, such as fear of fatness or pursuit of thinness. Moreover, perturbed body image is a common diagnostic category of anorexia and bulimia (DSM-IV-TR, CIM-10). Cooper et al. [Int J Eat Disord 6 (1987) 485-94] developed a one-dimensional, 34 items questionnaire in order to measure the worries about weight and shape of the body, called the "Body Shape Questionnaire" (BSQ). Its concurrent validity has been shown using the corporal dissatisfaction subscale of the eating disorders inventory (EDI) [Int J Eat Disord 2 (1983) 15-34], the drive for thinness and body dissatisfaction and the Eating Attitude Test (EAT) [Psychol Med 9 (1979) 273-79]. The total score of the BSQ ranges from 34 to 204. Lower scores indicate lower concerns about body shape. The BSQ provides a means of exploring the role of extreme obsession about the body's appearance in the development, pursuit and treatment of eating disorders. From this point of view, the BSQ is a tool widely used in research on the eating disorders. Recently, It has been validated in a French non-clinical population [Encephale 31 (2005) 161-73]. However, the validity of the BSQ has not been reported in patients with eating disorders in France. This was addressed in the present study. The first aim of this study was to assess perturbed body image with the French version of the BSQ in eating disorder patients. The second aim was to assess the sensitivity to change. The sample was composed of patients hospitalized for eating disorders (DSM-IV-TR). During their hospitalization, they were submitted to this questionnaire at the beginning and at the end of their care. The BSQ was compared with commonly used heteroquestionnaires such as the body dissatisfaction and drive for thinness subscale of the Eating Disorder Inventory (EDI-2), the Eating Attitude Test (EAT) and the Clinical Global Impression (CGI). Sensitivity to change was assessed by comparing total score at inclusion and at the end of hospitalization. Statistical analyses included Pearson's correlation coefficients, analysis of variance and t test. As Body Mass Index (BMI) can interfere with the BSQ score, it was included as confounding variables in the model in all analyses. Forty-five patients were included in the study. There were 21 patients with restricting subtype of AN, 17 patients with purging subtype of AN and seven BN. The mean age was 27.2+/-6.8 years, the mean length of hospital stay was 3.7+/-1.4 months, and the mean duration of the disorders was 10.7+/-6.3 years. The global BSQ score was high in the three groups of patients: 131.6+/-11.2. There was no significant difference between groups. There was no influence of the BMI on the BSQ scores. Correlation coefficient was significant for all scales with the BSQ except with the CGI. The higher correlation (r) was 0.58 with the drive for thinness subscale of the EDI-2. The change in scores between Day 0 and the end of hospitalization was significant (p<0.0001). The French version of the BSQ thus appears to be valid and accurate and should permit the study of perturbed body image in French eating disorder patients. However, sensitivity to change remains to be confirmed to evaluate response to treatment. Studies measuring this variable at different stages of the illness and recovery should be conducted.