An intracellular signal amplification strategy was developed for the quantification of ATP in single cells by microchip electrophoresis with laser-induced fluorescence detection. By using the method proposed, intracellular ATP levels in single HeLa, HepG2 and HL-7702 cells were found to be in the range of 30–150, 30–140, and 19–120 fmol per cell, respectively.