A new blind channel estimation scheme for orthogonal frequency division multiplexing systems is proposed based on the maximum likelihood principle. In the Blind channel estimation scheme, the blind channel estimator is proposed based on the noise subspace method and establishes conditions for blind channel estimation in spatially multiplexed MIMO-OFDM systems. A novel approach is also proposed for resolving the phase ambiguity of the blind channel estimate without the need for any reference symbols. Simulations were performed for mobile radio environments with high Doppler frequencies and short-to-medium delay spreads. The achieved performance is comparable to that of pilot-based channel estimation for the case of QPSK-modulation