['To demonstrate the use of the multifocal electroretinogram (mfERG) in addition to the full-field electroretinogram (ERG) in defining varying clinical pictures in children within a family with Bardet-Biedl syndrome (BBS).', 'All members from a family generation underwent a detailed history and examination before proceeding to a detailed ERG in accordance with the International Society of Clinical Electrophysiology for Vision protocol and a rapid, low-resolution mfERG. Of the sibling pair, the 13-year-old boy showed reduced vision and atypical maculopathy and the 10-year-old sister showed normal vision and atrophic maculopathy. Parents had normal ocular examination.', 'The male sibling had reduced rod and cone full-field ERG responses with a relatively spared central response from the mfERG suggesting central macular sparing. In contrast, for the female sibling, the ERG was normal for the cone pathway although reduced for rod pathway, with mfERG showing central involvement. The mother had rod responses at the lower end of normal range, a normal cone pathway, and a normal mfERG. The father showed a normal ERG and mfERG.'] Does multifocal electroretinogram contribute to differentiation of various clinical pictures within a family with Bardet-Biedl syndrome?