Wood frog (Rana sylvatica) is one of the few vertebrate species that have perfected the biological adaptations of surviving whole-body freezing when the temperature falls below 0°C in its natural habitat. It has been established that the metabolic rate is coordinated at different stages of the whole-body freezing of wood frog. Energy expensive and optional biological processes need to be repressed or completely shut down; while stress responsive pathways are activated. For example, overall gene transcription is largely suppressed during hypometabolism. This can be achieved at a genomic level via methylation at the C-5 position on cytosine residue of DNA (5mC). The present study explores DNA methylation in wood frog freezing survival by examining the protein expression levels and overall DNA methyltransferase activities of the major DNMTs in liver and muscle of both frozen and glucose-loaded wood frogs. The overall levels of 5′-methylcytosine and 5′-hydroxycytosine in muscle and liver genomic DNA are also compared between stress/glucose-loaded and control frogs. The results showed that freezing exposure led to increased protein levels of selected DNMTs in muscle ad liver of wood frog. In addition, the 5mC level dropped in liver but increased in muscle upon freezing exposure. The DNMT activity showed consistent changes in both tissues. Our data also suggest that high glucose (∼200mM) is able to inhibit overall DNMT activity in both tissues of wood frog. The present study demonstrated that response of DNMT-dependent DNA methylation is an integral part of wood frog freeze-tolerance.Source of funding: None declared.Conflict of interest: None declared.kenneth_storey@carleton.ca