Process; Balanced scorecard; Data envelopment analysis; cross efficiency; Goal programming; Lean Six Sigma.

Most of organizations use much of their focus and attention to solve problems, difficulties and weaknesses in their systems and processes to increase productivity and consequently to achieve sustainable competitive advantage in the global business arena. Organizations spend lots of time and resources to plan and develop their strategies; however most of them fail in the implementation of the strategy. Organizations try to achieve success through integrated performance of processes and technology to respond to the needs of their customers. Nowadays, application of Lean Six Sigma methodology is so applicable for organizations that operate in the competitive world. The importance of implementing the Lean Six Sigma in an organization is that the considered problem or process be discovered properly and selection of process beat the direction of organization's goals. In this way, organization can be targeted to take steps towards continuous improvement by improving the process performance.

The purpose of this research is choosing a strategic process through the Ghavamin Bank accounting group processes to improve the performance through application of Lean Six Sigma methodology. For this purpose, for selection of the process, first the criteria for choosing a strategic process were identified through six main measures of Balanced Scorecard and also by using the expert opinions. Consequently, information related to accounting group processes were collected through a database of Ghavamin Bank different units as well as interviews with Bank experts.Finally, using cross efficiency data envelopment analysis model, the performances of the processes were evaluated. The results showed that the process No. 18 ranked at the first place and it was introduced as the bank's strategic process to make continuous improvement in the Lean Six Sigma methodology.