To investigate the effects of sildenafil citrate (Viagra) on foveolar choroidal circulation in patients with age related macular degeneration (AMD). Double-blinded, randomized, placebo-controlled, crossover study. Fifteen male AMD patients received a dose of 100 mg of sildenafil or matching placebo on two separate days. Laser Doppler flowmetry was performed to assess relative choroidal blood velocity (ChB(Vel)), volume (ChB(Vol)) and flow (ChB(Flow)) in the study eye prior to administration of the drug at baseline and 30, 90, 180, 300 min after dosing. Best corrected visual acuity (BCVA), contrast sensitivity (CS), mean arterial blood pressure (BPm), heart rate (HR), intraocular pressure (IOP) and ocular perfusion pressure (PP) were determined. In comparison to placebo, sildenafil did not cause any statistically significant changes in mean ChB(Vel) (ANOVA, P=0.12), ChB(Vol) (ANOVA, P=0.24) or ChB(Flow) (ANOVA, P=0.46). There were no statistically significant changes in CS (ANOVA, P=0.59), BCVA (P=0.58), IOP (P=0.81) or HR (P=0.07) throughout the study. Significant decreases in BPm (P=0.006) and PP (P=0.006) were observed at 30 min after sildenafil. Administration of sildenafil citrate didn't cause any statistically significant changes in the foveolar choroidal circulation of AMD patients.