No single established cell line was found capable of substituting for primary baboon kidney (PBK) or primary rhesus macacque kidney (PRK) cells for detection of human viruses. Although a panel of cell lines could detect influenza, parainfluenza, and enteroviruses, which are among the most important viruses encountered in routine diagnostic laboratories, the sensitivity of this panel was not as high as that of PBK or PRK cells. However, in a promising complementary approach, PBK and PRK cells have been immortalised successfully by oncogene transfection, and some of the resulting cell lines have retained susceptibility to human viruses, and may be suitable for routine diagnostic use.