The nosology of the Laurence-Moon and Bardet-Biedl syndromes has been controversial. Presented is a patient with polydactyly, retinopathy, ataxia, low-average intellectual function, and obesity. These features constitute a composite of both syndromes and reflect the clinical heterogeneity that may be seen. Accordingly, the authors suggest the use of the term "Laurence-Moon-Bardet-Biedl phenotype" until these syndromes can be defined in some other manner. The neuroradiologic studies document atrophy of the cerebellum that accounts for the ataxia. Electroretinograms (ERG) demonstrate the decline in retinal function over a 16-year interval and the delayed cone ERG b-wave implicit time with normal cone amplitudes to 30 Hz white flicker that can exist in the early stage of this disorder.