Aim: To assess the relationship between childhood obesity and penetrative sexual abuse in girls. Methods: All obese girls referred to a hospital based pediatric endocrine unit were interviewed by a social worker or psychologist. Questions aimed to elicit any history of physical, emotional and sexual abuse are included. Overweight was defined as BM >95th percentile for age and gender. Body mass index (BMI) Z score (BMIZ) was calculated as measured BMI minus mean BMI for age and gender divided by standard deviation. Penetrative abuse was defined if a history was elicited of forced intercourse with any form of oral, vaginal or anal penetration. Results: A history of penetrative abuse was elicited in 5 out of 145 (3.5%) obese girls, their mean ± SD age was 11.9 ± 3.1 years. Abused girls were significantly more obese than the remainder of the patients (BMIZ 4.76 ± 1.34 vs. 3.39 ± 1.28 p = 0.02). Forty‐two of all girls had BMI Z scores ≥4, and of these four (9.5%) had been abused. All girls had changes in normal daily behaviour including seductive behaviour, seclusion, self‐mutilation and new onset day enuresis. Conclusion: In the evaluation of girls with marked obesity, particularly if associated with behavioural changes and failure to respond to therapy, the possible occurrence of penetrative sexual abuse should be considered.