It has been expected that CASE tools reduce programming efforts and increase development productivity. However, little has been reported on the analysis of the effect on productivity using quantitative data. This paper discusses productivity improvement through the use of an integrated CASE tool system named EAGLE (Effective Approach to Achieving High Leve Software Productivity), as shown by various data collected in Hitachi from 1980 through 1990. We have evaluated productivity by using three metrics, 1)program generation rate using reusable program skeletons and components, 2)fault density at two test phase, and 3)learning curve for the education of inexperienced programmers. We will show that productivity have been improved by the various facilities of EAGLE.