The use of tobacco and its products are known to cause many illnesses including cancer. A smokeless tobacco locally manufactured called tuibur (tobacco brew) has been consumed by the Mizos from a very long time. In this experiment we aim to determine the cytotoxicity of tuibur by an in vitro study on tuibur-treated human peripheral blood lymphocytes. We have found that 24 h treatment of human lymphocytes with two grades of commercial tuibur and nicotine showed a concentration dependent decrease in cell viability. We, therefore, concluded that as the in vitro use of tuibur has an adverse effect on cell survival, its consumption might have potential side effects on the health of the users.