The Vero cell line has been used by Pasteur-Merieux-Connaught (PMC) since 1982 with the Cell Bank's system to produce, at the 142nd passage, inactivated polio vaccine (IPV), oral polio vaccine (OPV) and rabies vaccines. The safety of the cell line has been regularly validated at the WCB level according to the WHO and European Pharmacopeia requirements for absence of bacteria, fungi, mycoplasma and viruses. Special emphasis was devoted to establishing the absence of simian viruses (SV40, SIV, Retro-D virus, simian CMV). Reverse Transcriptase (RT) activity was also negative. At low level of passage, the Vero cells are not tumorigenic. Vaccines have been prepared in low passage level Vero cells and, together with the excellent downstream purification, has resulted in excellent safety as attested by pharmacovigilance of more than 100 million doses of IPV during 12 years, more than 20 million doses of rabies vaccine during 10 years and more than one billion of OPV during six years.