The direct visualization of retinal vessels provides a unique opportunity to study cerebral small vessel disease, because these vessels share many features. It was reported that persons with smaller retinal arteriolar-to-venular ratio tended to have more white matter lesions on MRI. It is unclear whether this is due to arteriolar narrowing or venular dilatation. We investigated whether smaller arteriolar or larger venular diameters or both were related to severity and progression of cerebral small vessel disease. We studied 490 persons (60Â¿90 years) without dementia from a population-based cohort study. At baseline (1990Â¿1993), retinal arteriolar and venular diameters were measured on digitized images of one eye of each participant. In 1995Â¿1996, participants underwent cerebral MRI scanning. We rated the severity of periventricular white matter lesions on a 9-point scale, approximated a total subcortical white matter lesion volume (range: 0Â¿29.5 ml) and rated the presence of lacunar infarcts. On average 3.3 years later, 279 persons had a second MRI. Changes in periventricular and subcortical white matter lesions were rated with a semi-quantitative scale, and progression was classified as no, minor and marked. An incident infarct was a new infarct on the follow-up MRI. Neither venular nor arteriolar diameters were related to the severity of cerebral small vessel disease. Larger venular diameters were, however, associated with a marked progression of cerebral small vessel disease. Age and gender adjusted odds ratios (ORs) per standard deviation increase were 1.71 [95% confidence interval (CI): 1.11Â¿2.61] for periventricular, 1.72 (95% CI: 1.09Â¿2.71) for subcortical white matter lesion progression and 1.59 (95% CI: 1.06Â¿2.39) for incident lacunar infarcts. These associations were independent of other cardiovascular risk factors. Only the OR for incident lacunar infarcts was attenuated (1.24; 95% CI: 0.72Â¿2.12). No association was observed between arteriolar diameters and progression of cerebral small vessel disease. In conclusion, retinal venular dilatation was related to progression of cerebral small vessel disease. The mechanisms underlying venular dilatation deserve more attention, as they may provide new clues into the pathophysiology of cerebral small vessel disease.