Intracellular ice formation (IIF) propagates from cell to cell and causes lethal damage to the cell during the freezing process. In this study, we hypothesized that IIF passes through gap junctions between cells and that blockage of gap junctions increases cell viability after the freeze-thaw process because of the inhibited IIF propagation. Monolayer cultures of Madin-Darby canine kidney (MDCK) cells on glass coverslips were preincubated with and without the gap-junction blocker heptanol and subsequently frozen at different cooling rates on a temperature-controlled stage. Microscopic observations showed that IIF propagation was successfully inhibited in the blocked group. However, cell viability in the blocked group after thawing was significantly lower than that in the non-blocked group. Although results of this study did not confirm our hypotheses, they indicated the important role of gap-junctional communication in the occurrence of IIF and the consequent cell damage.