The article is dedicated to the analysis of the key factors that determine economic efficiency for manufacturing firms. This problem is solved, especially for businesses running under the conditions of a 'knowledge economy'. After a description of the specific features of a new economy, the authors have specified two main hypotheses: The first key factor which can cause general increase the level of economic efficiency is the management system and incentive scheme based on economic value added concept. The second factor should be a massive implementation and utilization of advanced manufacturing technologies. Both hypotheses have been verified in comparison to relevant opinions found in professional literature and to the results of a survey realized in 132 Czech manufacturing firms. The first hypothesis appears to be completely testified. The second hypothesis, related to advanced manufacturing technologies, has been confirmed only partly.