Familial Mediterranean fever is an autosomal recessively inherited disorder of unknown cause characterized by recurrent attacks of inflammation, involving mainly the peritoneum, pleura, synovia, and skin. Based on a phenotype analysis, we propose that its manifestations may be related to a genetic defect in one of the family of lipocortin proteins. Evidence is presented supporting an abnormality in the first step of prostaglandin/leukotriene synthesis.