Objective To observe the subfoveal choroidal thickness (SFCT) in eyes of patients with diabetic macular edema (DME).Methods Twenty patients (32 eyes) with DME were enrolled in this crosssectional observational study.The patients included 12 males and eight females,with a mean age of (47.3± 10.2) years.All the patients were examined documenting best corrected visual acuity (BCVA),spectraldomain optical coherence tomography (OCT) and ophthalmological examination.According to OCT DME morphology,samples are divided into diffuse macular edema,cystoid macular edema,serous retinal detachment and hard exudate groups.The SFCT was measured by a Cirrus HD-OCT with enhanced depth imaging (EDI) and was compared with the average SFCT (286.84 ± 28.80) μm of same age group.Correlation between SFCT and age,diopter,diabetic duration,fasting blood glucose,BCVA and central retinal thickness were analyzed by Pearson Analysis.SFCT of different DME types were analyzed by ANOVA Analysis.Results The mean SFCT of 32 eyes was (223.81±43.74) μm (ranging from 120.50 to 361.50 μm),which was lower by 63.03 μm (95％ confidence interval,-78.80 to-47.26 μm,P＜0.01)from normal SFCT.SFCT was independent of age (r=0.124),diopter (r=0.277),diabetic duration (r=0.286),fasting blood glucose (r=0.408),BCVA (r=0.087),and central retinal thickness (r=0.036).There was no significant difference of SFCT between different DME types (F =0.042,P ＞ 0.05).Conclusion SFCT is thinner in eyes with DME as compared to normal eyes of the same age.