**Abstract**

In the given chapter called Research of operational reliability of forest machines we deal with the reliability of forest machines in the field of logging, handling and removal of wood by world famous manufacturers. The main content of the work is the definition of the issue of operational reliability of forest logging machines, considering that this is very important for the high-quality and economical functioning of maintenance and diagnostics operations. The first part of the chapter focuses on an overview of current topics and thematic analysis. It describes the basics of operational reliability, maintenance and provide basic information about forest machines and their distribution. The second part deals with the reliability of specific forest machines. It discusses the methods and forms of maintenance, control of technological equipment and evaluation of operational reliability of forest harvesting machines.

**Keywords:** operational reliability, maintenance, means of transport, forest machines, transportation
