O'Hurley reprises his performance as silver-tongued lawyer Billy Flynn.
The musical also welcomed a host of other alums to mark the milestone occasion.
Bebe Neuwirth, James Naughton, Joel Grey, and Ann Reinking will celebrate by making cameos in tonight's show.
From New York to California, the stars are coming out to reclaim their theatrical roots.
Tony Award winner John Rando will direct.
Durang will star opposite Marilu Henner in his play this summer at the New Hope Theater.
Marilu Henner and Christopher Lloyd were on hand to celebrate Danny DeVito and Judd Hirsch's opening night in the Neil Simon comedy.