In this paper, we present a blind algorithm for joint estimation of symbol timing offset (STO) and carrier frequency offset (CFO) for orthogonal frequency division multiplexing (OFDM) systems with I/Q imbalance. The proposed algorithm exploits the cyclostationarity of OFDM signals and relies on second-order statistics only. Estimation performance of the algorithm is evaluated by simulation and the results obtained in some typical scenarios are provided to show its effectiveness.