In this paper, we develop a new carrier frequency offset (CFO) estimation scheme for interleaved orthogonal frequency division multiple access (OFDMA) transmission. We employ multi-antenna at the receiver and exploit the rank reduction approach to blindly estimate the CFOs of multiple users. The proposed scheme supports full load transmission that allows all sub-carriers being allocated to users, which is a significant advantage over the existing schemes. Both performance analysis and numerical results are provided to corroborate the proposed studies.