A thread that owns a mutex can specify the same mutex in repeated wait function calls without blocking its execution. The number of calls is kept by the common language runtime. The thread must call Mutex.ReleaseMutex the same number of times to release ownership of the mutex.

If a thread terminates while owning a mutex, the mutex is said to be abandoned. The state of the mutex is set to signaled and the next waiting thread gets ownership. If no one owns the mutex, the state of the mutex is signaled. Beginning in version 2.0 of the .NET Framework, an System.Threading.AbandonedMutexException is thrown in the next thread that acquires the mutex. Prior to version 2.0 of the .NET Framework, no exception was thrown.

In the case of a system-wide mutex, an abandoned mutex might indicate that an application has been terminated abruptly (for example, by using Windows Task Manager).