Autosomal-recessive retinitis pigmentosa (arRP) was recently associated with mutations in a novel gene EYS, spanning over 2 Mb, making it the largest known gene expressed in the human eye. The purpose of this study was to establish the prevalence and nature of EYS mutations in a clinically well-characterized cohort of 239 sporadic and arRP French cases. Direct sequencing of EYS was performed in 186 subjects for whom known mutations had previously been excluded by applying microarray technology. We mostly identified novel mutations in EYS in a total of 29 patients: Fifteen of the mutations were predicted to create premature stop codons and two represent exonic deletions. In addition, twenty missense, silent or splice-site mutations were detected. Patients revealed homozygous or compound heterozygous mutations and in some cases, only a single mutation. Most patients showed classical signs of RP with relatively preserved central vision and visual field until late in the course of the disorder. One patient showed predominance of the disease in the inferior part of the retina suggesting potential phenotypic variability. With a prevalence of 12% or more we provide evidence that EYS is a major gene for RP in France and probably elsewhere. © 2010 Wiley-Liss, Inc.