This paper considers resource allocation in OFDM wireless networks with mixed real-time and non-realtime traffic patterns. We employ a utility-based framework to balance efficiency and fairness, while satisfying QoS requirements of real-time users. A utility function is assigned to each user over each sub-carrier; this indicates the transmission priority for the user/sub-carrier pair based on the achievable rate and experienced delay, subject to delay and power constraints. The proposed scheduler gives in one shot the sub-carrier and power allocation, plus transmission scheduling for each time-slot. Simulation results indicate that while satisfying real-time users' delay requirements, the proposed method achieves a significant performance improvement in terms of overall throughput and fairness.