The goal of this study was to evaluate the virus inactivation efficacy during the chemical process of deacetylation of chitin to chitosan. Chitosan is a N-deacetylated derivative of chitin, which used in wide varieties of biomedical application due to its beneficaial properties such as low toxidity, biodegradability, anti-tumor, and bacterial activity, and etc. The deacetylation proess of chitin is an essential step in obtaining chitosan, which results in enhanced solubility and functionality. Th virus inactivation efficiency of the deacetylation process was evaluated using two relevant viruses, white spot syndrome virus (WSSV) and hepatitis A virus (HAV), commonly associated with shellfish that is common sources of chitin. These viruses were deliberately inoculate into chitin and the deacetylation reaction was performed by adding 50% NaOH and heating at 90 °C for 2h. The deacetylation process of chitin inactivated majority of both viruses. A factor of 106.5 was inactivated for WSSV reduction (i.e. 6.55 log10) and 104.8 factor was inactivated for HAV. These results demonstrate that the deacetylation process of chitin is sufficient in inactivating viruses so that the end product, chitosan, can be used as a virus-free biomedical polymer safe use in humans.