A self-sealing needle injection hub has two resilient, elastomeric sealing members mounted adjacent one another in a housing, both having pierced passages through which a needle can be inserted. The outer member is thick and relatively rigid; the inner member is thinner and flexible. Both members are radially compressed by the housing, the inner member bowing away from the outer member at its center. The action of withdrawing a needle from the hub, combined with the pressure of blood on the inner member, maintains the inner member flat against the outer member, thereby further compressing the passage through the inner member.