A Brazilian stock of clone C17 of the IB-RS-2 porcine kidney cell line which was contaminated with hog cholera virus (HCV) was cloned. One clone designated IB-RS-2 D10 was determined to be free of HCV, 20 other viruses, and Mycoplasma. IB-RS-2 D10 cells possessed the same viral susceptibility pattern as the contaminated parent cells to the viruses of foot-and-mouth disease, swine vesicular disease, vesicular exanthema of swine, transmissible gastroenteritis, and several other viruses. The IB-RS-2 D10 cells had a median chromosome count of 34, were morphologically epithelioid cells, and were resistant to HCV infection. Freedom from HCV affords advantages for vaccine production and avoids laboratory contamination.