OBJECTIVES: The relationship between obesity and psychological health remains unclear. The aims of this study were to evaluate the effect of obesity on the psychological health of a non-clinical sample of obese women, to investigate binge eating in this group, and to examine the predictors of psychological distress. DESIGN: A cross-sectional comparison of women divided into three obesity groups (body mass index (BMI) = 30-34.9, 35-39.9, greater than or equal to 40) was used. PARTICIPANTS: 179 women with a BMI > 30 (mean age 45y) returned a questionnaire included in a subscriber-only magazine for women of size 16+. MEASURES: The questionnaire asked for information on demographics, weight history and eating behaviour, and included established self-report measures of body shape assessment, body shape satisfaction, dietary restraint, mental health state and self-esteem. RESULTS: The heaviest women (BMI > 40) did not differ on measures of mental health, but expressed the greatest dissatisfaction with their body weight, shape and appearance, and had the lowest self-esteem. Frequent binge eating was reported by 25% of all women. Self-esteem and peer relationships, but not body weight, were highly significant negative predictors of poor mental health. CONCLUSIONS: Poor mental health is not the inevitable consequence even of the most extreme obesity, but is related to both low self-esteem and poor peer relationships. These, and problems with eating control, are features of psychological morbidity that require recognition and therapeutic attention.