The 1979 vintage marked the first release of Opus One, a joint venture between pioneering Californian winemaker Robert Mondavi and the late Baron Philippe de Rothschild. This, the 1991 vintage is a blend of Cabernet Sauvignon 93%, Cabernet Franc 6%, and Merlot 1%, aged for 15 months in new French oak. The vintage yielded wines of great structure and balance with a sweet middle palate, layering fruit and oak aromas.