Ti-49 at.% Ni thin films developed by magnetron sputtering were annealed under different conditions. Two types of precipitates, the FCC Ti2Ni and HCP TiNi3, were found to exist simultaneously in the annealed films. Their size, distribution and morphology can be strongly affected by the annealing conditions. The phase transformation behavior was recorded by a standard d.c. method. The martensitic transformation temperatures of annealed films were much lower than those reported for TiNi films, which may possibly be explained by the small size of grains and precipitates, the close distance between precipitates and the orientation of some TiNi3 precipitates. With the intensification of annealing conditions, the martensitic transformation temperature was increased. The changed size and distribution of precipitates were used to explain this tendency.