The RadMenuItem control provides you with a standard ICommandSource implementation. This means that you can bind your items to commands that will get executed when an item is clicked. For this purpose you can use the following properties.
Command - gets the command that will be executed when the command source is invoked.
CommandParameter - represents a user defined data value that can be passed to the command when it is executed.
CommandTarget - the object that the command is being executed on.
As the RadMenuItem implements the ICommandSource, you can use it with any command that implements the ICommand interface, for example the DelegateCommands in Prism.
By default the command of a RadMenuItem will not be executed for RadMenuItems which have child RadMenuItems. If you wish to change this behavior, you can set the NotifyOnHeaderClick property of the RadMenu to True. This way, even if a RadMenuItem has child items, its corresponding command will be invoked on click.