This paper presents a blind frequency offset estimation algorithm for OFDM systems. The blind algorithm is compared to two popular frequency offset estimation algorithms. The first is the cyclic prefix-based (CPB) algorithm, which is blind but does not perform well in frequency selective channels. The second is the the pilot tone-aided (PTA) algorithm, which performs well in frequency selective channels but requires pilot subcarriers. Unlike the CPB and PTA algorithms, the blind algorithm in this paper does not require any training symbols or pilot subcarriers, and performs well in frequency selective channels. By simulation, it is shown that the performance of the blind algorithm is better than that of the PTA algorithm with subcarriers comprised of 25% pilot subcarriers anti 75% of data subcarriers.