Trypsin is supposed to the influenza virus into host purpose of this study is to determine the role of t rypsin process of the influenza H1N1 virus in Vero and MDCK (M Kidney) cells; to see whether trypsin receptor-mediated endocytosis or non viruses were inoculated into Vero and MDCK cells under three conditions: (1) without trypsin in the medium trypsin (VTVi1 and MTVi1) inoculation and incubated with medium containing tr ypsin (VTVi2 and MTVi2). Advance cytopathic effect HA (hemag glutination) titer cells. Moreover, HA titer on MTVi1 was higher than MVi, and the lowest was found on MTVi2. Trypsin supported the internali the cleavage of HA glycoprotein halt the internaliz ation of with trypsin before virus inoculation. Trypsin coul d digest protein containing sialic aci Conversely, trypsin did not Vero cells based on HA titer. This result was also supported b y TEM observation, which showed that influ enza virus is very low. We sugges 2,6)-containing receptor on the membrane of virus internalization. On the other hand, active internalization of the virus was seen in all groups of MDCK cells (MVi, MTVi1, and MTVi2). However, trypsin could not trigger the internali cells via non-receptor- mediated endocytosis. From this study it can be con cluded that trypsin enhanced the cleavage of the hemagglutinin (HA) of the virus, but did not improv e the ability of the host cells to internalize the virus, especially via non endocytosis.