Purpose: To evaluate the early effects of dexamethasone implant in patients with diabetic macular edema (DME). Methods: Eyes with DME were prospectively included in the study. Best-corrected visual acuity (BCVA) measurement, complete ophthalmic evaluation, and spectral-domain optical coherence tomography were performed at baseline and 1, 2, 3, 7, 14, 21, 28, 60, and 90 days after treatment. Results: Twenty-three eyes of 20 patients were included in the study. Mean central retinal thickness (CRT) decreased rapidly after treatment (p < 0.0001, repeated measures ANOVA) from 511 μm at baseline to 469 μm after 1 day (p < 0.05), and 275 μm (p < 0.01) at the end of the follow-up. BCVA gain (p < 0.0001, repeated measures ANOVA) was on average +2 ETDRS letters at day 1 (not significant), +9 letters from day 28 to day 90 (p < 0.01). Conclusion: Intravitreal dexamethasone implant showed an early and fast effect in reducing CRT and improving BCVA in DME patients.