PURPOSE To investigate whether rhegmatogenous retinal detachment (RRD) alters intraocular soluble syndecan-1 levels. METHODS In all, 39 samples of subretinal fluid (SRF) and 10 samples of vitreous fluid from RRD patients were collected. Using ELISA, soluble syndecan-1 levels were detected, and potential correlations between syndecan-1 levels with clinical parameters were analyzed. RESULTS Soluble syndecan-1 in the vitreous fluid (2.577+/-0.578 ng/ml) and in the SRF (1.499+/-0.184 ng/ml) from eyes with RRD enhanced significantly compared to that of the controls (0.224+/-0.095 ng/ml) (p<0.0001 and p=0.006). An increase in the syndecan-1 concentrations in SRF samples correlated with a longer duration of retinal detachment (r=0.716, p<0.0001) and a younger age (r= -0.341, p=0.017). CONCLUSIONS RRD was found to be associated with a significant increase of soluble syndecan-1 in the vitreous fluid and SRF. In SRF, an enhanced soluble syndecan-1 concentration correlated positively with the duration of retinal detachment and inversely with the age of patients.