Health regulator Monitor is to investigate the board of mental health organisation South London and Maudsley NHS Foundation Trust following concerns about its effectiveness.
The regulator said it was acting after external reviews of the trust raised concerns over how the board is organised and run.
Monitor’s investigation will also examine whether the trust has robust and effective systems in place to identify and rectify any potential problems with the quality of care for patients.
Regional director Mark Turner said: "Our focus will be on whether the board is providing strong enough leadership to ensure that patients always receive quality care."
A spokesman for the trust said: "We welcome the opportunity to examine our board governance and we share the regulator’s aims of providing strong leadership and ensuring our patients always receive quality care.
"SLaM provides the widest range of mental health services in the UK and we are delighted to have the chance to work with Monitor in reviewing our systems to ensure they are continually refreshed and improved upon."