Introduction. Useful life time studies are important to define the duration of food, and necessary for not overestimate or underestimate the real life time of the product. Objective. To determine the useful life time of low calories cream cheese under physic, chemical and sensory terms. Materials and methods. With two fat substitutes (Z-trim and Paselli SA2) at three different concentrations each, it was calculated which one of them did not cause significant changes in the cream cheese in a sensory level with proofs aimed to consumers and instrumental by the use of a texture analyzer TA-XT2i, comparing them with a pattern cream cheese sample elaborated with no fat substitute. Results. The substitute with the best behavior in relation to the parameters mentioned above was Z-trim at 0,5%. Conclusion. The useful life time of the product can be established in three months, given the fact that the results obtained in the sensory proof are more representative.