The accuracies of unstructured grid methods for flutter analysis were investigated. Time accurate flow simulations with moving boundary were carried out on three types of unstructured grids. The results are compared with a recent report obtained by a structured, parallel flow solver. Semi-structured triangular grids and isotropic fine grids show similar results and agree well with the data. Poor grid resolution can result in wrong responses of the wing motion near the flutter boundary even when the same grid distribution is used on the wing. Typical wing responses for the lower- and higher-frequency modes are elaborated.