There is disclosed a strain-relief adapter for relieving strain between a cable or harness and a connector. The strain-relief adapter consists of a flexible, generally tubular body of braided nonmetallic filaments, attachment means on one end of the tubular body for attaching the tubular body to a connector and a blocking sleeve on the other end of the tubular body for attaching the tubular body to a cable or harness. The blocking sleeve includes a heat-shrinkable tube and an adhesive.