Thirty-nine members of one family, covering three generations, were HLA-typed. Twenty-five suffered from primary diffuse articular chondrocalcinosis, and all had the same dominantly transmitted autosomally controlled disease. This was characterized by acute articular attacks, which always started before the age of 35, and radiologically by typical cartilaginous and fibrocartilaginous deposits associated with para-articular calcifications. The lesions were both peripherally and axially generalized. None of the 28 HLA antigens tested seemed related to the disease, nor did the disease segregate with an HLA haplotype.