Background and Aims: During the last years a new Foreskin cell line strain (RFSC) has been isolated, characterized and stored in a representative cell bank stock in liquid nitrogen as a part of HCB (Human Cell Bank) development program in Razi institute. Materials and Methods: The cell population was serially passaged for mass production purpose based on WHO schedule .The controls on pool samples were carried out upon our sampling method and international recommendations. Results: The data concerning parameters as well as the result of compulsory controls on Kario logy oncogenicity, cross contaminations, species specificity, no oncogenicity, and mycoplasma free of a human cell line that contained heteroploid chromosomal characterizations are performed. Conclusion: Kariological examination found an obvious discrepancy in the frequency of aberrations due to high passage level that produced a heteroploid continuous cell line. Virus susceptibility shows RFSC-1 more sensitive to RS#12 Mumps virus strain. This cell line is completely sterile and has no any cross contamination to other pathogen and can be used for production and control of Mumps vaccine.