To evaluate the long-term efficacy and factors involved in the recurrence and persistence of subretinal fluid (SRF) after half-dose photodynamic therapy (PDT) for chronic central serous chorioretinopathy (CSC). In this retrospective observational case series, 79 eyes (73 patients) with chronic CSC were treated with half-dose PDT and followed up for at least 3 years. They were divided into successful (64 eyes) and unsuccessful (15 eyes) groups based on SRF absorption and disease recurrence after one PDT session. Age, best-corrected visual acuity (BCVA), central foveal thickness, neuroretinal thickness, height of SRF, subfoveal choroidal thickness, window defect area detected by fluorescein angiography, and PDT spot area were compared between the groups. Factors associated with PDT success and BCVA at 3 years were investigated. LogMAR BCVA improved from 0.21±0.24 to 0.08±0.16 (P<0.001) at 3 years after PDT. Compared with the unsuccessful group, the successful group had a significantly younger mean age (50.5±9.7 vs. 56.5±9.1 years, P = 0.032) and better baseline BCVA (0.18±0.23 vs. 0.32±0.25, P = 0.034). Other parameters were not significantly different. Multivariate analyses showed that unsuccessful PDT was significantly associated with lower baseline BCVA (P = 0.026) and older age (P = 0.029) and that BCVA at 3 years after PDT was positively associated with baseline BCVA (P<0.001). Half-dose PDT has a long-term efficacy in chronic CSC. Relatively early PDT may improve anatomic and functional outcomes of chronic CSC.