Purpose: We studied the choroidal circulation in patients with proliferative diabetic retinopathy (PDR) to assess whether choroidal hemodynamic abnormalities may exist in PDR. Methods: Eighteen eyes of 18 patients with PDR and high-risk characteristics for visual loss were included in this study. Mean duration of diabetes was 20 ± 9 years (mean ± SD), hemoglobin A1c was 8.9 ± 2.3%, and blood glucose at the time of blood flow measurement was 188 ± 90 mg/dl. Choroidal circulatory parameters obtained in these patients were compared to those of 35 eyes of 35 age and blood pressure matched, healthy controls using a Wilcoxon rank sum test. Laser Doppler flowmetry (Oculix) was used to calculate relative choroidal blood velocity (Ch_vel), volume (Ch_vol), and flow (Ch_flow) in the center of the foveola. Results: No significant differences in average age, mean blood pressure (BP_m), or perfusion pressure (PP) were observed between diabetic patients and control subjects. In diabetic patients, Ch_vol was 0.29 ± 0.08 (mean ± 1 SD) arbitrary units (AU); this value was 15% lower than that of control subjects, 0.34 ± 0.10 AU (p = 0.04). In contrast, average Ch_vel was not significantly different between subjects with PDR (0.39 ± 0.07 AU) and control subjects (0.41 ± 0.07 AU). The average Ch_flow in subjects with PDR (9.4 ± 2.9 AU) was 27% lower than that of control subjects (12.8 ± 4.2 AU; p = 0.003). No significant correlation was detected between the circulatory measurements and age, BP_m, or PP. There was a statistically significant negative correlation between duration of diabetes and Ch_vel (R = −0.55; p = 0.03). Conclusions: Our results suggest that Ch_vol and Ch_flow are significantly reduced in patients with PDR.