The rescue of influenza viruses by reverse genetics has been described only for the influenza A and B viruses. Based on a similar approach we developped a reverse genetics system that allows the production of influenza C viruses entirely from cloned cDNA. The complete sequences of the 3´ and 5´ non coding regions of type C influenza virus C/Johannesburg/1/66 necessary for the cloning of the cDNA were determined for the seven genomic segments. Human embryonic kidney cells (293T) were transfected simultaneously with seven plasmids, that direct the synthesis of each of the seven viral RNA segments of the C/JHB/1/66 virus, under the control of the human RNA polymerase I promoter and with four plasmids encoding the viral nucleoprotein and the PB2, PB1, and P3 proteins of the viral polymerase complex. This strategy yielded between 10(3) and 10(4) plaque forming units of virus per ml of supernatant at 8-10 days post-transfection. Additional viruses with substitutions introduced in the HEF protein were successfully produced by this method, and their growth phenotype was evaluated. This efficient system, which does not require helper virus infection should be useful in viral mutagenesis studies and to generate expression vectors from type C influenza virus.