A two-dimensional finite element model of a typical tailor-welded tube (TWT) with two different thicknesses is built up, in which the weld is included into the model as the third segment of the tube blank. Hydroforming processes in a die with an equal inner diameter and in a die with two different inner diameters are simulated. The bulging and thinning behavior of the TWT and the effect of the thickness difference and the weld on the forming process are discussed. The weld displacement and possible initial cracking position are predicted. In a die with an equal diameter, the position of the weld plays an important role on the forming process. In the die with two diameters, the weld should be kept in the region with the smaller diameter, to avoid cracking in the weld or heat affected zone. With a tailor-welded tube, the weight of a tubular component can be reduced.