In this paper, we discuss third-order edge-based schemes for unsteady problems. Secondand third-order unconditionally-stable implicit time-integration schemes, BDF2 and ESDIRK3, are compared, and effects of different orders of time accuracy are examined. Numerical results indicate that the orders of accuracy in time and space need to match to fully take advantage of the low-dispersive feature of third-order edge-based schemes. Furthermore, the third-order scheme combined with a low-dissipation numerical flux is shown to serve as a simple and economical scheme for high-resolution simulations. The third-order low-dissipation edge-based scheme has been implemented in NASA's FUN3D with a low-dissipative Roe flux, and demonstrated for a three-dimensional unsteady viscous flow over a cylinder. Results indicate that the third-order time-accurate edge-based scheme with a low-dissipation Roe flux is a practical approach to high-fidelity unstructured-grid simulations over complex geometries.