From the trypsinized skin of a rabbit embryo, a fibroblastic cell line has been obtained (FEL cells). The primary seed lot has been established at 11th passage. The tests for tumorigenicity on nu/nu mice were negative (10(4) cell/animal) at passage level 11th and 50th. Cell growth and morphology were not altered when 100 passages were performed. FEL cells were tested for their susceptibility to rabies virus. The production of virus on FEL cells was investigated after infection by the P.V. rabies virus strain adapted to several cell types (bovine fetal kidney, Vero and BHK cells). For the evaluation of an experimental rabies vaccine produced with this substrate, FEL cells were compared to Vero cells. The synthesis of glycoprotein (EIA) and the immunogenicity (NIH test) were similar for the vaccines obtained with both cell systems. FEL cells could therefore be an alternative to Vero cells for the production of a cell culture inactivated rabies vaccine.