The diabetogenic potential of the human isolate, Coxsackievirus B4 (CB4) (Edwards) was studied in three inbred mice strains, SWR/J, DBA/2, and C57BL/6. The mice were infected with this agent and evaluated for mortality, pancreatic histopathology, and glucose tolerance. Results showed that the mortality induced by CB4 in these inbred strains differed considerably. There was no evidence of a correlation between virus-induced mortality and virus-induced pancreopathy. Although CB4 (Edwards) was most lethal to C57BL/6 mice, based on the infecting 50 per cent lethal dose (LD50), this mouse strain developed no pancreatic pathology. The most severe pancreopathy, i.e., acinar necrosis with acute interstitial inflammation and islet atrophy, was observed in SWR/J mice, which had an intermediate susceptibility to virus-induced mortality. DBA/2 mice, which displayed the lowest susceptibility to virus-induced lethality, showed less pancreatic pathology (i.e., acute and chronic interstitial inflammation) than SWR/J mice. IN SWR/J mice, virus-mediated alteration in glucose homeostasis was expressed by an increase in glucose tolerance 7 and 21 days after infection. In contrast, C57BL/6 mice showed a tendency toward chemical diabetes at 21 days postinfection. This study suggests that CB4-induced mortality and pancreatic pathology are independent parameters and do not necessarily determine the glucose tolerance of a given host genotype.