The RAB small G protein family is composed of approximately 40 members. Many of them are ubiquitous and are expressed and participate in transport processes, such as endocytosis and exocytosis, whereas others are expressed only within a specific cell group carrying out specific functions. In the current study, we present the molecular characterisation and chromosomal location of the human RAB23 gene, a new member of the RAB family. This gene, expressed in retina, is composed of 7 exons spanning 34 kb of genomic DNA and located in the pericentromeric region of chromosome 6 between microsatellite markers D6S257 and D6S1695, within the critical region of RP25. Since proteins belonging to the Rab family have already been related to retinal degeneration we considered RAB23 an interesting candidate for the RP25 locus. However the absence of pathogenic variations after molecular analysis of the coding sequence in the index patients of RP25 linked families would be consistent with the exclusion of RAB23 as responsible for RP25 phenotype.