Since the current implementation of read_write_mutex still is suffering from a known bug (which has not been fixed since pre1.33) I ask if it should also be removed from 1.34 branch. The read_write_mutex has not been part of 1.33 exactly for this reason. We plan to provide a rewritten one for 1.35, but it is not yet stable enough (i.e being extensively reviewed and tested). The alternative would be to deliver it in 1.34, but putting a big fat warning. Also it could be marked in the regressions as "unexpectedly passing", so users would not get a wrong impression. Unfortunately no test case yet exists, that is able to trigger the error for sure. The below links refer to the bug: http://lists.boost.org/Archives/boost/2005/08/92307.php http://lists.boost.org/Archives/boost/2005/09/93180.php Please let me know what you think. Roland