The default install of RubyMine (v.2.0.2) doesn’t know about IronRuby so you have to configure it.
Navigate to the bin directory of your IronRuby installation and select ir.exe
RubyMine will interrogate IronRuby to determine its Ruby version and update the display
The default project configuration in RubyMine adds some parameters to the command line that IronRuby may not recognize, so remove them as follows:
Clear the “Ruby arguments” box and click OK
Close the configuration window
If you have already created projects in RubyMine you have to each project and update the command line arguments as follows: