Purpose: To assess the short term effect of an intravitreal dexamethasone implant on diabetic macular edema (DME) with epiretinal membrane (ERM). Methods: We conducted a retrospective study including 39 eyes of 39 patients with DME who underwent intravitreal dexamethasone implant injection and were able to be observed for more than 6 months. Patients were divided into two groups according to presence or absence of ERM from March 2015 to June 2016. Results: Thirteen DME eyes with ERM and 26 DME eyes without ERM were enrolled. The classification of ERM was grade 0 in 5 (38.5%) eyes, grade 1 in 7 eyes (53.8%) and grade 2 in 1 eye (7.7%). There was no difference in best corrected visual acuity (BCVA) and central macular thickness (CMT) between the DME with ERM group and the DME without ERM group at baseline. After the injection, there was no difference in mean BCVA and mean CMT between the two groups at 1, 3, and 6 months. DME without ERM group showed a significant decrease in CMT compared to baseline at 1, 3, and 6 months (p < 0.001, p = 0.003, p = 0.001, respectively). The DME with ERM group showed a significant decrease in CMT compared to baseline at 1 and 3 months, but no difference at 6 months (p = 0.048, p = 0.024, p = 0.275, respectively). Conclusions: Intravitreal dexamethasone implantation may be a useful treatment modality for patients with DME with ERM, but the duration of the anatomical improvement may be shorter than that for patients with DME without ERM.