Hi Christophe and All after splitting our complicated several level deep contained state machines to small run-time instances. I have to use feature Event Hierarchy (http://svn.boost.org/svn/boost/trunk/libs/msm/doc/HTML/ch03s02.html#d0e1176) which is really cool. But this feature in combination with pseudo exits state, breaks the pseudo exit state functionality and the pseudo exit state is entered but never left. I have made a small example where the problem is reproduced see attachment. (the file name is misleading was just lazy to rename it something more appropriate) Here is the output of the execution : entering: Idle MS1_ leaving: Idle Action: MS1::onEvent1 entering: RunningStateMachine MS1_ entering: RunningStateMachine::PseudoEntry1 leaving: RunningStateMachine::PseudoEntry1 entering: Inner1 RunningStateMachine_ entering: InnerState11 leaving: InnerState11 leaving: Inner1 entering: RunningStateMachine::PseudoEntry1 I have tried it in our host test environment only so VC9 compiler and with boost trunk from Friday last week. Cheers Richard.