As lean principles have been shown to be one of the most effective to get competitive advantages in manufacturing, almost every enterprise tries to apply lean principles in all functional departments. Although various quantitative and qualitative measures are used to assess the effectiveness of lean implementation in each functional department, a single composite measure would assist management in evaluating the leanness level of entire organization. In this paper, we develop a method to calculate a single integrated leanness index by integrating the every quantitative and qualitative lean measures used in various departments of an enterprise. This method takes into account the relative importance of each measure by pairwise comparison, and uses fuzzy logic to consider the fuzziness of lean attainment shown by each measure. The derived integrated index will make it easier to determine leanness level of a single organization as a whole and will facilitate comparison of lean achievement between different organizations. The developed procedure is applied on the case of a previously published paper (Cho et al. [3]) to show an example of calculating process.