Recently competitiveness of companies has been based less on such production factors as the capital or human resources, whereas the importance of the knowledge factor is growing. What is particularly important is not the knowledge itself but an ability to integrate it in the company. Practice shows that it is necessary to introduce an advanced system of knowledge management in companies. It is not an easy task, though, because knowledge is present in all aspects of the company operation. Therefore management should not be treated as an additional, isolated and independent activity, but as an inseparable part of all business processes. This work contains some suggestions connected with assessment of knowledge management effectiveness and efficiency and considerations referring to such terms as 'knowledge' and 'knowledge management'.