Abstract— This paper proposes a maximum likelihood detection (MLD) method for the differential space-time block code (DSTBC) in cooperation with blind linear prediction (BLP) of fast frequency-flat fading channels. The method, which linearly predicts the fading complex envelope, determines the linear prediction coefficients by the method of Lagrange multipliers, and does not use decision-feedback nor require information on channel parameters such as the maximum Doppler frequency in contrast to conventional ones. Computer simulations under a fast fading condition demonstrate that the proposed method with a proper degree of polynomial approximation can be superior in BER performance to a conventional method that estimates the coefficients by the RLS algorithm using a training sequence.