Hyperphosphatemic tumoral calcinosis (HTC) is a rare inherited metabolic disorder manifested by pararticular calcification and hyperphosphatemia, caused by an elevated renal phosphate reabsorption threshold and elevated serum 1,25-dihydroxyvitamin D levels. The disorder usually affects African-American subjects, but has also been described in Caucasians and Hispanics. Vascular calcifications and angioid streaks have been reported to be associated with the disorder; however, dementia has not been previously reported. Our medical center has followed two African-American siblings, with HTC for over 30 years, who have developed dementia at 56 years and 67 years of age. Neither man has been hypertensive, however, magnetic resonance imaging (MRI) scans in both cases revealed multiple periventricular infarcts, suggestive of infarcts caused by vascular calcification in the central nervous system. These two brothers with HTC suggest that periventricular infarcts with dementia may be a long term complication of this disorder.