This study measures and compares the profit and cost efficiencies of Thai commercial banks between 1990 and 2008 which has been subdivided into the precrisis,the financial crisis, and the postcrisis periods. The efficiency scores are measured using a combination of parametric and nonparametric frontier approach. Both average profit and cost efficiency levels of the postcrisis period are found to be significantly lower than those of the precrisis period. The evidence also indicates that the real GDP growth rate and some general and financial characteristics are correlated with the efficiency level of Thai commercial banks.