The aim of this study was to evaluate PXF (pentoxifylline; 1600 mg daily vs placebo) in patients with retinal vein thrombosis (RVT) in a 4-week trial, evaluating clinical outcome and retinal flow. Inclusion criteria were sudden loss of vision (SLV); retinal vein thrombosis (RVT); decrease in retinal vein flow; asymmetry between retinal veins (>40%) documented by duplex scanning (retinal vein thrombosis flow = RVTF). All 18 included patients completed the study. The groups were comparable. No side effect was observed. An improvement in arterial flow (p<0.05) and a decrease in analogue score (p<0.05) were observed in both groups (due to the spontaneous evolution with partial thrombus lysis in 4 weeks). The increase in arterial flow (PSF and EDF) were greater (p<0.05) in the PXF group. The RVFV increase was better in the PXF group (350% increase vs 200% increase in the placebo group; p<0.05). There was a significant difference in the analogue score decrease (4 vs 7) in the PXF group (p<0.05). In conclusion, PXF improved retinal flow after RVT better than placebo. It should be considered as an important treatment option.