The aim of this study was to analyse epigenetic (specifically, DNA methylation) change in testes induced by maternal exposure to di-2-(ethylhexyl) phthalate (DEHP) in mice. Testicular dysgenesis syndrome was induced in foetuses by maternal exposure to DEHP. High-performance liquid chromatography was performed to analyse DNA methylation status, and expression levels of the DNA methyltransferases were examined by quantitative real-time polymerase chain reaction and western blotting. DEHP significantly had more than 10% relative increase in the global DNA methylation and also increased DNA methyltransferases' expression. Changes in DNA methylation may play an important role in abnormal testicular function caused by environmental factors such as maternal exposure to DEHP, which may be one possible mechanism of DEHPmediated testicular toxicity.Adverse trends in male human reproductive health have been observed in many countries in the last few decades. Reproductive disorders like cryptorchidism, hypospadias, low sperm counts and testicular cancer may be increasing in incidence [1][2][3]. According to Skakkebaek, these interrelated disorders may be symptoms of a common condition, human testicular dysgenesis syndrome (TDS), and that originates before birth [4]. The increasing release of synthetic chemicals in the environment may underlie human TDS, particularly phthalate esters, which are the most abundant produced plasticisers, leach out from polyvinyl chloride (PVC) and disrupt androgen action [5,6]. Di-2-(ethylhexyl) phthalate (DEHP) is the most common phthalate for producing flexible PVC and present in a wide variety of consumer products [7]. According to recent biomonitoring studies, exposure of the general population to DEHP is widespread and higher than previously assumed [8][9][10]. Interestingly, reproductive toxicity induced by perinatal exposure of experimental animals to DEHP has remarkable similarities with the symptoms of human TDS [5,6,11]. Like human TDS, the disturbances caused by DEHP are downstream consequences of altered Sertoli and Leydig cell functions during development, and inhibit testosterone (T) and insulin-like growth factor 3 (INSL3) production [5,11,12]. The mechanism of DEHP-mediated toxicity on testis, however, is still unclear. One possible mechanism is that DEHP metabolites bind to peroxisome proliferator-activated receptors (PPAR) [13]. But the action of DEHP on testis cannot explain entirely by a PPAR-mediated pathway, because PPAR-knockout mice remain sensitive to phthalate-mediated reproductive toxicity [14].Mammals contain numerous cell types, with the majority having identical genomic sequences. Genetic information is the sequence of DNA bases itself, whereas epigenetics encodes information without changing the DNA sequence [15]. Epigenetics involves multiple mechanisms such as DNA methylation, histone acetylation and chromatin modification to control cell development and differentiation. Methylated cytosine guanine dinucleotide (CpG) in CpG islands of promoter areas re...