Project management is of high significance for companies nowadays. This is of special interest for those organizations which operate in the multi-project environment. For them, it is crucial to find out how good they are at managing projects. To that end, the project management maturity assessment concept was developed. However, getting a picture of the organization is only the first step. The second should be to analyze the results and, based on them, undertake appropriate activities in order to increase efficiency in project management. There are various models of project management maturity (PMM) assessment in different areas. In investigating current management trends, the knowledge management concept is one of the most important ones. Therefore, in author's opinion the modern PMM model should definitely address the knowledge management area. In the article based on the world-wide empirical study of 400 companies, I discuss the PMM level in the knowledge management area. The assessment was done using the author's PMM model which measured maturity in four areas: methods and tools, human resources, project environment and knowledge management. The investigated companies were from the machinery, construction and information technology branches. The major research effort was focused on the machinery industry as this sector of the economy is not well recognized in empirical research related to project management. Moreover, the main aim of the study was to compare Polish and foreign companies via an examination of diverse industries. The results of the study revealed that, in general, the foreign companies are at a higher PMM level in the knowledge management area than their Polish counterparts. This difference is discussed in the article. Among the industries, the most mature was information technology and this is also elaborated on. In addition, the study shows that the mean maturity level of all investigated companies is rather small. The reasons for that fact are explained and the implications for the companies are outlined.