With the aim of improving ductility through structural modification, first-principles calculations have been carried out to study the effect of ternary additions of 3d transition metals on the structural stability of Ti3Al. It is found that all the ternary transition-metal additions substitute preferentially for Ti atoms in Ti3Al. Our calculations predict that V and Cr are potent β stabilizers, whereas Zr, Ni and Cu (with about 10 at. %) can stabilize Ti3Al into the L12structure. Both modified cubic structures can possibly provide improved ductility compared with that of Ti3Al with the hexagonal D019structure. It is also found that the electronic density of states at the Fermi level plays an important role in determining the structural stability.