The invention provides a human or humanized anti-CD38 antibody or functional fragment thereof, wherein said antibody or functional fragment thereof is able to mediate killing of a CD38+ target cell by ADCC with an at least five-fold better efficacy than chimeric OKT10 under the same or substantially the same conditions when a human PBMC cell is employed as an effector cell, wherein said CD38+ target cell is selected from the group consisting of LP-1 and RPMI-8226, and wherein the ratio of effector cells to target cells is between about 30:1 and about 50:1. The invention further provides a human or humanized anti-CD38 antibody or functional fragment thereof, wherein said antibody or functional fragment thereof is able to mediate killing of a CD38-transfected CHO cell by CDC with an at least two-fold better efficacy than chimeric OKT10 under the same or substantially the same conditions. The invention further provides a human or humanized anti-CD38 antibody, wherein said antibody binds to an epitope of CD38 comprising one or more amino acid residues of amino acid residues 1 to 215 of CD38. Nucleic acids encoding the antibodies of the invention as well as therapeutic uses of the antibodies are also provided.
