Lattice corneal dystrophy type I (LCDI) is a relatively common corneal dystrophy which can cause severe visual impairment. Recent studies have suggested a genetic localisation for the disease to chromosome 5q. Independent genetic linkage analysis in a six generation LCDI pedigree confirmed linkage to the 5q region bounded by marker loci IL9 and D5S436 suggesting genetic homogeneity. A maximum two point lod score of 7.51 (theta = 0.03) was obtained with marker D5S393. Multipoint and haplotype data positioned the disease between loci D5S393 and D5S396 corresponding to a genetic distance of 2cM, thus refining linkage sufficiently to allow for physical mapping of this disorder.