In this brief, a new noncoherent chaos-based communication scheme, named high-efficiency differential chaos shift keying (DCSK) (HE-DCSK), is proposed. By recycling each reference sample in DCSK, 2 bits of data can be carried in one data-modulated sample sequence, which offers our scheme double bandwidth efficiency and nonrepeated transmitted signal less prone to interception in comparison to DCSK. The bit-error performance of the proposed scheme is studied analytically based on Gaussian approximation for discrete-time implementations. Simulations in additive-white-Gaussian-noise channel are performed and compared with DCSK and correlation delay shift keying (CDSK) schemes. Results show that the bit-error rate performance of HE-DCSK can always outperform CDSK and be even better than DCSK with typical spreading factors and at reasonable E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> /N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> levels.