In this paper the fatigue strength of frame and tank of the railway tank car was estimated. Calculations were carried out by finite element method. Since high difficulty of mentioned calculations the tank and frame were calculated separately. Lifetime of tank of the railway tank car was estimated on the basis of the damages from the vertical and longitudinal dynamic loads at the different schemes of constraints. Lifetime of frame of the railway tank car was calculated on the basis of the safety factor at the rolling due to longitudinal irregularities of the railway track.