To examine the distribution and clinical ophthalmic characteristics of pseudoexfoliation syndrome (pseudoexfoliation) and glaucoma in Icelandic families.Icelandic families containing three or more members aged 70 or older with at least one member with pseudoexfoliation were identified. All family members over age 45 were invited to participate. Visual acuity, Goldmann applanation tonometry, gonioscopy, slit lamp examination before and after dilatation, and dilated fundus examination were performed on all available family members. Pertinent data were obtained from medical records, including ophthalmic history and a medical history of cardiovascular disease, cerebrovascular disease, systemic hypertension, and diabetes mellitus. Participants were classified according to affected status for pseudoexfoliation, glaucoma, and age related macular degeneration.Six families were identified who met the criteria for entry into the study. Of 94 family members who were invited to participate 82 were enrolled (87%). Of these 25 (30%) had pseudoexfoliation syndrome, 51 (62%) were unaffected, and six (7%) were suspects. At least one individual with pseudoexfoliation was identified in the second generation of every family. A parent with pseudoexfoliation was identified in all cases either by examination (4/6) or a review of ophthalmic records (2/6). In all cases the mother was the affected parent. The prevalence of glaucoma was significantly greater in the group with pseudoexfoliation (p <0.0001). Although the presence of age related macular degeneration (ARMD) was highly associated with the presence of pseudoexfoliation, the significance was lost after correction for age (p = 0.69). Although the sample size was small, no association between pseudoexfoliation affected status and cardiovascular disease, cerebrovascular disease, systemic hypertension, or diabetes mellitus was found.Multiple Icelandic families with pseudoexfoliation in two generations were identified. In all cases where determination was possible, transmission to the second generation was through an affected parent. In each case the affected parent was the mother. Pseudoexfoliation was strongly associated with the presence of glaucoma, but was not associated with either ARMD or systemic disease in this study. These data clearly indicate that pseudoexfoliation is a familial condition and although not conclusive, supports the hypothesis that pseudoexfoliation syndrome is genetically inherited.