This paper describes the influence of a combination of nisin and carvacrol on the membrane potential, the pH gradient and the intracellular ATP pools of vegetative cells of Bacillus cereus. Both the membrane potential and the pH gradient were dissipated by nisin and carvacrol. The intracellular ATP pool was rapidly depleted. In combination, carvacrol enhanced the membrane potential, dissipating the activity of nisin, and acted synergistically in dissipating the pH gradient and depleting the intracellular ATP pool. The synergistic depletion of ATP could not be explained by an increased ATP efflux, indicating that carvacrol does not enlarge the pores formed by nisin or increase the lifetime or the number of pores.