This is a report on the feasibility of dead time correction of single-ion-counting data in time-of-flight mass spectrometry. Here signals vary on a time scale similar to the dead time of the detector. The correction of dead time effects based on the Poisson distribution is practicable for single peak integrals. This leads to a sufficient correction for most applications like the measurement of isotope, element, and molecule ratios or ion imaging. Even the exact dead time correction of total mass spectra is possible but requires the precise knowledge of the dead time. This is, in general, not a fixed time interval but has to be described by a probability function.