Watermelon fruit was found to be rich in α-mannosidase (EC 3.2.1.24) and β-N-acetylhexosaminidase (EC 3.2.1.52). A simple procedure has been devised for the simultaneous isolation of α-mannosidase and β-N-acetylhexosaminidase from watermelon fruit. The purified enzymes were electrophoretically homogeneous and sufficiently free from other glycosidases. The molecular weights of α-mannosidase and β-N-acetylhexosaminidase were estimated to be 270, 000 and 150, 000 by Sephadex G-200 gel filtration. The enzymes had their maximum activities at pHs 4.0-4.5 and 5.0-5.5, and their Km values for the corresponding p-nitrophenyl glycoside were 2.3 and 0.65mM, respectively. α-Mannosidase required Zn2+ to retain its activity and liberated 60% of the mannose from ovalbumin glycopeptide.