Objective To make the diagnosis of a pedigree of X-linked congenital stational night blindness(CSNB) and to identify the disease-causing gene. Methods Clinical examination and family analysis were made. Venous blood was drawn from 5 affected and 16 unaffected individuals from the family. Genomic DNA was extracted. The locus of the candidate gene was mapped by linkage study. Mutation was screened by polymerase chain reaction (PCR) of the candidate gene exons and flanked introns. The PCR products are directly sequenced. The healthy people in and out of the family who were selected according to certain standards were as the control. Results A Chinese family with X-linked complete congenital stationary night blindness (CSNB1) was diagnosed. A missense mutation A772C (T258P) in exon 2 of NYX gene was identified in all affected patients and all female carriers were heterozygous. This mutation was neither found in normal family members nor among 110 unrelated normal controls. Conclusion A novel mutation of NYX gene with threonine to proline change is responsible for this Chinese CSNB1 family. (Chin J Ocul Fundus Dis, 2007, 23: 184-188)