We and others have previously shown that human and avian influenza viruses infect and replicate in HAE [13, 14, 31] . Since our previous experiments were performed at 37uC, a temperature reflective of human distal airways, we have now compared human and avian influenza virus infection and growth in HAE at temperatures reflective of the proximal airways (32-33uC) and distal airways (37uC). HAE were inoculated at either 32uC or 37uC with a low multiplicity of infection (MOI; 0.01) of a representative human virus, A/Victoria/3/75 (H3N2), or an avian influenza isolate, A/Dk/Eng/62 (H4N6). Virus growth and spread throughout the epithelium at the two temperatures was measured and compared over time and infection further characterized with respect to virus-induced cytopathic effects (CPE).