AbstractIt is proposed that when cells are either attached to, or very near, a rupturing bubble, the hydrodynamic forces associated with the rupture are sufficient to kill the cells. Four types of experiments were conducted to quantify the number and location of these killed cells. We determined: (1) the number of cells killed as a result of a single, 3.5‐mm bubble rupture; (2) the number and viability of cells in the upward jet that results when a bubble ruptures; (3) the number of cells on the bubble film; and (4) the fate of cells attached to the bubble film after film rupture. All experiments were conducted withSpodoptera frugiperda(SF‐9) insect cells, in TNM‐FH and SFML medium, with and without Pluronic F‐68. Experiments indicate that approximately 1050 cells are killed per single, 3.5‐mm bubble rupture in TNM‐FH medium and approximately the same number of dead cells are present in the upward jet. It was also observed that the concentration of cells in this upward jet is higher than the cell suspension in TNM‐FH medium without Pluronic F‐68 by a factor of two. It is believed that this higher concentration is the result of cells adhering to the bubble interface. These cells are swept up into the upward jet during the bubble rupture process. Finally, it is suggested that a thin layer around the bubble containing these absorbed cells is the “hypothetical killing volume” presented by other researchers. © 1994