Dear John,

I'm assuming that when you say "Requiem Mass" you are referring to the great musical works.  YES, they are still used in Catholic churches in the United States, but it is somewhat rare.  They may be used at funeral Masses or at any Mass of the Dead.  They are indeed "connected" to the Mass as the text is (or at least should be) exactly the official text for the Mass, usually in Latin.

Some parishes have a small orchestra or a visiting orchestra called a sacred orchestra that plays these great works.  The Second Vatican Council ordered that this sacred music be preserved in the Catholic Church.  (not all orchestral masses are masses for the dead)  More often than not these works are performed by secular orchestras but they do indeed have a place in church on Sunday morning or at other times.  Masses for the Dead such as Mozart's Requiem for example can be used at Mass on Nov. 2, All Souls day.  It can also be played at someone's funeral or at another Mass of the Dead.

I believe that most of the great musical mass settings for the dead were actually composed for a specific person such as a king or queen.  If parish has the talent, they can be used for anyone.

Mr. Slavek.