Four pairs of first-degree relatives with polymyalgia rheumatica, giant cell arteritis, or both have been encountered among approximately 250 such patients. Two of these pairs were mother-daughter combinations, the first such cases to be reported. Chance alone is unlikely to account for this association. The possible roles of environmental, genetic, and immunologic factors are considered.A clear relationship has been established in recent years between polymyalgia rheumatica and giant cell arteritis (temporal arteritis, cranial arteritis) (1-4). Both occur in older patients, are associated with systemic signs, respond exceptionally well to corticosteroid therapy, and share characteristic laboratory findings including a fast erythrocyte sedimentation rate, hypopro-