Abstract： Objective To determine the quantitative changes of choroidal thickness in central serous chorioretinopathy.Methods Cross-sectional study.Twenty-three patients with unilateral central serous chorioretinopathy (CSC) in acute and chronic stages were diagnosed after fluorescein angiography,indocyanine angiography and enhanced depth imaging optical coherence tomography (EDI OCT).EDI OCT scan across the fovea was performed in each eye and the result was compared with that from an age-,sex-matched and spherical equivalent-matched control subject.Subfoveal thickness of choroid was calculated by a onboard software in HRA2.Results Choroidal thickness in the CSC eyes and the fellow eyes was (464.43 ±97.15) μm and (399.91 ± 124.01) μm,respectively.No significant difference between the two groups (t =4.653,P ＜ 0.05).Choroidal thickness was (313.09 ± 70.67)μm in the control group.There was statistically significant difference in thickness between the CSC goup and the control group (t =5.077,-2.085 ;P ＜ 0.05).Choroidal thickness in the fellow eyes with choroidal vascular hyperpermeability was (506.44 ± 75.66) μm,which was differed significantly(t =4.749,P ＜ 0.05) from the non-hypermeability eyes (331.43 ±97.94)μm.Conclusions Subfoveal choroid thickness in the symptomatic eye and the fellow eyes in CSC gruoup is thicker than that of the control group.The subfoveal choroidal thickness of eyes with hypermeability is thicker than that in the non-hypermeability eyes.EDI-OCT is a noninvasive procedure which can be used to evaluate the choroidal hypermeability in CSC.