The paper turns an attention to the problems of code generators in advanced CASE tools from the UML class diagram. Authors give a general introduction to code generator types, describes their structure and principles of operation. Three tools are analyzed within the correspondence to their abilities to generate program code from the UML class diagram. They are two modeling tools, namely, Sparx Enterprise Architect and Visual Paradigm, and the programming environment Microsoft Visual Studio .NET. Program code is generated from different fragments of the UML class diagram in all three tools and the obtained code lines are compared with the expected ones based on the model semantics and syntax of the programming language C#. Authors summarize the results of the practical experiments with code generation by stressing different types of errors in the generated code and make conclusion about the directions of the evolution of code generators in the close future.