This study reports the results of a survey about the improvements achieved as result of ISO 14000 Environmental Management System (EMS) standard implementation and the differences of improvements with respect to firm characteristics. A survey has been conducted in order to explain the improvements related to environmental management process and overall firm performance. The survey involved sixty-six enterprises implementing ISO 14000 EMS standard in Turkey. In order to assess improvements obtained from ISO 14000 EMS implementation, statements related to environmental management process and overall firm performance indicators have been prepared. The statements in this study are relevant to previous research. A factor analysis was employed to determine the factors of the variables explaining improvements. Nine factors have been identified related to achieved improvements, such as establishment of pro-active environmental management system, effectiveness in resource utilization, effectiveness of process control, relationships with industry and government, meeting expectations of stakeholders, demonstration of social responsibility, profitability, productivity, and competitiveness. Then, a T- test was conducted to determine the differences of managers’ assessments with respect to certain firm characteristics. The findings have shown that there are differences in the assessments of improvements achieved as a result of ISO 14000 EMS standard implementation with respect to sales volume, foreign-capital possession, and ISO 14000 EMS standard implementation. On the other hand, industrial sector, age of establishment, and export orientation are not statistically significant for the differences in the assessments of improvements.
