Bardet-Biedl syndrome (BBS) (MIM 209900) is a genetic disorder with a wide spectrum of clinical manifestations including retinal dystrophy, hypogenitalism, polydactyly, obesity, renal abnormalities and mental retardation. We describe a 13-year-old girl, a known case of Bardet-Biedl syndrome, who was going to undergo hysterectomy due to hydrometrocolpous. She was homozygous autosomal recessive for gene BS57. She was obese and had impaired vision, renal abnormality, borderline intelligence, recurrent urinary tract infection, menstrual problems, normal secondary sex chrematistics and corrected polydactylies. She had also big nose, thin upper lip, slightly everted lower lip, small mouth and retrognathia. Her electrocardiography showed incomplete right bundle branch block. We identified atrioventricular septal defect (AVSD). In conclusion, physicians who deal with cases who suffered from Bardet-Biedl syndrome, should be vigilant about seeking for identification of cardiac anomalies such as partial AVSD. This leads to earlier identification of the existing cardiovascular disease which facilitates appliance of curative measures.