The study is to investigate impacts of corporate governance on the performanceof Thailand 's financial institutions. We focus on the role of stockholders andcreditors. We use the fixed effect model with panel data, covering the periodsbetween 1993 and 1997 data for bank sector and 1993 and 1996 for finance sector. Inaddition, we adopt Tobin's Q as a proxy of companies' performance. We first study the structure of stockholders of financial institutions. The60-65% of banks major stockholders. The percentage of institutional investors, whichis about 50-60%, experiences an increasing trend. For finance companies, majorstockholders is stable at the level of about 63%. While the share of institutionholding, which is around 45-55%, shows a declining trend. Among major shareholders,the percentages of equity holding by financial institutions are about 25% in banksand 50% in finance companies. In bank sector, we find that the size of major shareholders, both individualand institution major shareholder, and the creditors have positive impact on banks'performance. However, the size of equity held by other finance institution has nosignificant of the performance. In finance sector, we find that size of equity held by domestic banks lead to adecline in the performance of finance companies. In addition, the size of financecompanies result in lower Tobin's Q. Growth of overall economy shows a positiveimpact on the performance of banks and finance companies. We conclude that policies or measures regarding promotion of major stockholdersand restrictions on bank stockholdings in finance companies may improve corporategovernance of Thailand's financial institutions.