Varicella-Zoster virus (VZV), which causes Chicken Pox and Zoster, belongs to the Herpes viridae family [1, 2]. The virus is strongly cell dependent and its in vitro stability is very low. Following Takahashi's work, we have developed and prepared a vaccine with the OKA strain virus in the Japanese stabilizer. To improve the stability of the virus in a freeze-dried form, we have finalized a new formulation of stabilizer, called V 15-1. This stabilizer is a protein-free solution with defined contents of amino acids, salts and sugars. Comparative stability studies between the Japanese stabilizer and V 15-1 have been performed at different temperatures. We have demonstrated good stability for two years at + 5 degrees C and at + 25 degrees C and + 37 degrees C for the vaccine in freeze-dried form. We have also found a good stability of this vaccine at + 5 degrees C and + 25 degrees C after reconstitution. The use of V 15-1 thus allows us to prepare a Varicella vaccine with the OKA strain (> 2000 PFU per dose) which has good stability at 5 degrees C. A Varicella vaccine using a live attenuated virus strain OKA was developed in 1974 by Takahashi in Japan [3, 4]. The virus was isolated from vesicular fluid collected from a child with chicken pox. After propagation in human embryonic lung cells (HEC), guinea pigs embryonic cells (GPE) and human diploid cells (WI 38), the virus was attenuated. All the licensed vaccines are prepared with the OKA strain [5].