By entering the knowledge age and the appearance of knowledge economy, organizations are more dependent on knowledge workers productivity. Productivity means doing the right things right. It shows how a knowledge worker makes use of resources to fulfill the goals of the organization. This definition makes productivity be the result of simultaneous existence of efficiency "doing the things right" and effectiveness "doing the right things". Since factors influencing knowledge workers productivity cannot be definitely measured, uncertainty theory plays an important role in this area. So in this paper, first, dimensions of productivity will be introduced and then, by the use of linguistic fuzzy approach and DEA, efficiency and effectiveness of knowledge workers will be measured. Next, a model for measuring knowledge workers productivity will be presented on the basis of efficiency and effectiveness. Finally, values of knowledge workers productivities will be ranked. In the last section, the result of this five-step method is examined through a case study.

knowledge worker, productivity, efficiency, effectiveness, fuzzy DEA