AbstractPresentation of different influenza virus antigens generates different immune responses. Intranasal immunization with either live (VA) or formalin‐inactivated (VF) A/PR/8/34 (HoN1) influenza virus induced local as well as peripheral cell‐mediated immune response (CMI), as evidenced by elevation in3H‐thymidine incorporation. Cell‐mediated immune response was detected as soon as 24–48 hr following the application of VA and 4–5 days following VF. Cell‐mediated immune response in both instances peaked on the 12th day and disappeared between 16 and 20 days after application.Local CMI response was threefold higher after immunization with VA (SI = 28.6) than with VF (SI = 9.4), while VF induced higher peripheral response (32.0 vs 17.7). The mononuclear cell population in the lungs increased, correlating with a rise in the stimulation index (SI). The percentage of IgA surface‐bearing B lymphocytes was significantly higher following IN administration of VA, but not following VF instillation. This corroborated the finding that VF failed to induce local antibody response in the lungs in spite of its capacity to stimulate humoral antibody and CMI responses.Mice immunized intramuscularly with both viral preparations developed a fair humoral antibody response without detectable CMI (perip