Toxicoepigenomics is new field emerged from the combination of toxicology and epigenetics. It is defined as the heritable changes in the gene activity induced by exposure to environment and toxicant substances such as heavy metals without any alterations in the existing nucleotide sequence. Research studies show that epigenetics plays important role in the development of certain human diseases such as diabetes and cancer. Hence toxicoepigenomics has evolved as an important new area in toxicology research. In toxicoepigenomics targeting DNA methylation alteration as a tool to identify the underlying causes of disease development exists as important trend in the current research design, but this aspect of toxicoepigenomics has been evaluated extensively. New mechanisms such as microRNA (miRNA) dysregulations need to be considered for future research work. Furthermore, it is important to consider different study designs such as the application of parallel in vitro and in vivo studies. This might be an interesting aspect of toxicoepigenomics research and will enable researchers to fill the gap in the existing research designs.