Ratio analysis allows a hospital to evaluate its own performance over time and to compare its performance with that of other hospitals. For this study, three types of ratio analysis were conducted based on some data on hospitals in Massachusetts. First, Key ratios influencing financial performance were identified using discriminant analysis. Second, the financial structures of the teaching and the non-teaching hospitals were compared using ratios and multiple comparison method. Third, the effects of the prospective reimbursement law of the state on financial performance were examined using ratios and paired t-test. The purpose of the law is to reduce hospital costs by setting the revenue ceiling prior to the effective budget year. The findings of this study were as follows: 1) When hospitals were divided into three groups, according to their operating income, only profitability ratios showed a consistent difference among the groups. 2) In the discriminant analysis, five ratios were selected: current ratio, operating margin, return on assets, fixed assets turnover, and inventory turnover. They are the key ratios to be monitored periodically for the purpose of evaluating the financial performance of hospitals. 3) When teaching hospitals were compared with non-teaching hospitals, acid ratio, days of cash on hand, and inventory turnover were statistically significant before the law went into effect, whereas only fixed assets turnover and inventory turnover were significant afterward. Contrary to previous studies, profitability ratios of teaching hospitals were higher than those of non-teaching hospitals, although the differences were not statistically significant. 4) When the ratios between the two periods (before and after the law) were compared, three profitability ratios (operating margin, return on assets, and return on equity) were significant for teaching hospitals, whereas three activity ratios (total assets turnover, fixed assets turnover, current assets turnover) were significant for non-teaching hospitals. Furthermore, while both total operating revenue and expenses were decreased, net operating income was increased, due to a greater decrease in total operating expenses. This shows that the law can indeed, simultaneously, achieve both a reduction in costs as well as an improvement in the financial situation of hospitals.