Importance: Blood pressure lowering is considered neuroprotective in patients with cerebral small vessel disease, however more “intensive” regimens may increase cerebral hypoperfusion. We examined the effect of intensive vs. standard blood pressure treatment on cerebral perfusion in severe small vessel disease patients. Objective: To determine whether intensive vs. standard blood pressure lowering over 3 months causes decreased cerebral perfusion. Design, Setting and Participants: This randomised, parallel, controlled, blinded-outcomes clinical trial took place in 2 English university medical centres. A central, online randomisation system (1:1 ratio) allocated grouping. 70 hypertensive patients with MRI confirmed symptomatic lacunar infarct and confluent white matter hyperintensities were recruited between 2012 and 2015, and randomised (36/34 in standard/intensive arms). Analysable data were available in 62 patients, 33/29 in the standard/intensive groups respectively, for intention to treat analysis. This experiment examines the 3 month follow-up period. Intervention: Patients were randomised to “standard” (systolic=130-140mmHg) or “intensive” (systolic=<125mmHg) blood pressure targets, to be achieved through medication regimen changes. Main Outcome and Measure: Cerebral perfusion was determined using arterial spin labelling; the primary end point was change in global perfusion between baseline and 3 months, compared between treatment groups by ANOVA. Linear regression compared change in perfusion against change in blood pressure. MR scan analysis was blinded to treatment arm. Results: Patients were 69.3 years old (mean) and 59.7% male. Mean(SD) systolic blood pressure reduced by 8(12) and 27(17)mmHg in the standard/intensive groups, respectively (p<0.001), with achieved pressures of 141(13) and 126(10) mmHg respectively. Change in global perfusion did not differ between treatment arms: standard, mean(SD) (ml/min/100g)= -0.5(9.4); intensive, 0.7(8.6), partial ETA2= 0.004, 95% CI= -3.6–5.8, p= 0.63. No differences were observed when analysis examined grey/white matter only, or was confined to those achieving target blood pressure. The number of adverse events did not differ between treatment groups (standard/intensive mean(SD)= .21(.65)/.32(.75), p=.44). Conclusions and Relevance: Intensive blood pressure lowering did not reduce cerebral perfusion in severe small vessel disease.