Steady flows of rarefied gases through orifices, slits, short tubes, and channels are well studied. In spite of the high practical interests to the transient flows of rarefied gases, the problem of short tube flow has not been studied from this viewpoint. The aim of the present work is to study transient rarefied gas flow through a short tube on the basis of the direct simulation Monte Carlo method. The mass flow rate and flow field are calculated as a function of the time in the transitional and hydrodynamic regimes with respect to the gas rarefaction. Two values of the pressure ratio, i.e., 0.1 and 0.5, and two values of the aspect ratio, i.e. 1 and 5, are considered. A characteristic time equal to that needed to cross the tube radius with the most probable molecular speed is introduced. The typical time to establish the stationary flow is calculated. The flow field past the tube reaches the steady state during the same time in the transitional regime and it takes a longer time in the hydrodynamic regime.