Multi-time wave functions such as φ(t 1 , x 1 , . . . , t N , x N ) have one time variable t j for each particle. This type of wave function arises as a relativistic generalization of the wave function ψ(t, x 1 , . . . , x N ) of non-relativistic quantum mechanics. We show here how a quantum field theory can be formulated in terms of multitime wave functions. We mainly consider a particular quantum field theory that features particle creation and annihilation. Starting from the particle-position representation of state vectors in Fock space, we introduce multi-time wave functions with a variable number of time variables, set up multi-time evolution equations, and show that they are consistent. Moreover, we discuss the relation of the multi-time wave function to two other representations, the Tomonaga-Schwinger representation and the Heisenberg picture in terms of operator-valued fields on space-time. In a certain sense and under natural assumptions, we find that all three representations are equivalent; yet, we point out that the multi-time formulation has several technical and conceptual advantages.Key words: Tomonaga-Schwinger equation; many-time formalism; particleposition representation of quantum states; consistency of multi-time Schrödinger equations; relativistic wave functions; wave functions on spacelike hypersurfaces; operator-valued fields; Heisenberg picture in quantum field theory.