Objective To explore K 562 cell apoptosis induced by cord blood CD 3AK cells and CD 3AK cell cultural supernatants (CS). Methods Apoptosis was detected in K 562 cells and in K 562 cells cultured with either cord blood CD 3AK cells or CS using the TDT end labelling technique, cell morphology and DNA agarose gel electrophoresis. Results The percentage of apoptotic cells in the control K 562 culture was 3.50 ± 0.97% . Apoptosis of K 562 cells cultured with CD 3AK cells rose to 27.38 ± 4.91% (P< 0.01 ). Culturing K 562 cells in CS also resulted in significantly increased apoptosis ( 33.09 ± 5.22% ) (P< 0.01 ). Conclusions Cord blood CD 3AK cells and CS could induce K 562 cell apoptosis. [