Background/Aims: To study the effectiveness of intravitreal ranibizumab injection (IVR) in the treatment of acute central serous chorioretinopathy (CSCR). Methods: A Prospective, randomized, single-center, parallel-arm, controlled trial study the involved patients had symptoms of CSCR with less than 3 months duration. Patients (n = 50/ divided into 2 groups) the anti-VEGF group with 30 patients injected with intravitreal Ranibizumab(IVR) (0.5 mg/0.05 ml) and an observation group where 20 patients were observed, each group were followed for 4 months. Best-corrected visual acuity (BCVA), and central macular thickness (CMT) were assessed by Ocular coherent tomography (OCT) for first baseline and then at regular follow-ups. Results: All patients had improved and increased BCVA, with decreased CMT, and resolution of the subretinal fluid. The mean CMT in IVR and observation groups was 117.33±46.2μm and 196.70±36.9μm, respectively (P = 0.670) The mean BCVA and mean CMT improved significantly in both groups at 4 weeks , but the changes were not significantly different between both groups at 4months. Conclusions: both IVR and observation for acute CSCR improved the resolution of subretinal fluid. BCVA and CMT did not differ at 4 months, between IVR and observation groups. So we advised a Further studies are required to determine the long-term benefits of IVR.