The associations of plasma fibrinogen level with age in members from longevity families and non-longevity families were compared and the influences of relationship in family members to plasma fibrinogen level were analysed to study the relationship between plasma fibrinogen level and life-span run in family. MEANS: The authors measured fibrinogen in 156 Uygur subjects from 7 longevity families and 9 non-longevity families. Fibrinogen level was relatively stable among different age groups in longevity families. It was an association positively with age in non-longevity. Fibrinogen level of children was closely correlative with parent's. Genetic factor probably contributes to plasma fibrinogen level. Plasma fibrinogen level correlates with life-span run in family.