A computer stylus may have an elongated body with a tip and an opposing end having components such as a connector and an antenna. Metal structures for the antenna may be supported using a molded plastic support with metal traces or may be formed using flexible printed circuits or other structures. Metal and plastic tubes may be used in forming the body of the stylus. A metal tube may have an opening in which an antenna is mounted. A plastic tube may serve as an outer housing for the stylus and may cover the metal tube and the opening in which the antenna is mounted. A transmission line such as a cable may be coupled to an antenna feed. The cable may pass through an opening in the metal tube and may be covered using a strip of conductive foam.