The mosquito-borne disease dengue is caused by four serologically- and genetically-related viruses, termed DENV-1 to DENV-4. Historical setbacks due to lack of human-like mouse models of dengue were partially remedied with characterization of lethal DENV-2 infection in immunocompromised AG129 mice (deficient in IFN-α/β/γ receptors). Recently, our group established lethal AG129 mouse infection models of DENV-1, DENV-3, and DENV-4 using human isolates. Here we compare a non-lethal, disseminated model of DENV-3 infection using strain D83-144 to that of the lethal outcome following infection by strain C0360/94. Both strains belong to DENV-3 genotype II and differ by only 13 amino acids. Intraperitoneal inoculation of AG129 mice with strain D83-144 led to clinical signs of dengue infection, such as cytokine induction, thrombocytopenia, and systemic infection. However, C0360/94 infection led to features of severe human dengue, including coagulopathy and lethal outcome, whereas D83-144 infection does not. This study is the first to investigate a low passage, non-mouse lethal strain in AG129 mice and demonstrates that D83-144 infection induces milder features of human dengue than those induced by lethal C0360/94 infection. The results suggest that the AG129 mouse model has applications to investigate factors associated with mild or severe disease.