A clinical and radiographic survey of 110 members of 2 families with hereditary pyrophosphate arthropathy was performed. The mode of inheritance was autosomal, dominant with a variable penetrance. Twenty-two percent of the family members had joint involvement related to pyrophosphate arthropathy, 47% of those over 50 years of age had experienced acute attacks of arthritis and/or had joint calcifications. The majority of individuals with both arthritis and joint calcifications suffered from chronic pain that resulted in early retirement. A high frequency of back pain was observed, but no ankylosis or deformity. Surgery was performed for parathyroid hyperplasia on the propositus in 1 family, and several members of her family suffered from symptoms that suggested a disturbance of calcium phosphate metabolism. There were several differences between our patients and 50 cases of sporadic pyrophosphate arthropathy from the same area of Sweden. Familial cases had an earlier onset, a greater number of involved joints, and peripheral joint involvement more often. Back pain was more frequent, and calcifications of intervertebral discs were found only in the hereditary cases.