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Over 1 million tons of grapefruit were processed in 2003/04 resulting in 500,000 tons of peel waste. Grapefruit peel waste is usually dried, pelletized, and sold as a low-value cattle feed. This study tested several different loadings of commercial cellulase and pectinase enzymes to hydrolyze grapefruit peel to produce sugars that can be fermented into ethanol and other products. Pectinase and cellulase loadings of zero, one, two, five, and ten mg protein/g peel dry matter were tested. All hydrolyses were supplemented with 2.1 mg beta-glucosidase protein/g peel dry matter to hydrolyze cellobiose produced by cellulase and pectinase. Five mg pectinase/g peel dry matter and one mg cellulase/g peel dry matter were the lowest loadings to yield the most total sugars. Theoretical ethanol yields for grapefruit peel were lower than previous studies utilizing orange peel due to less dry matter in grapefruit peel than in orange peel.