BACKGROUND AND PURPOSE: The roles of blood low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides in the development of post-stroke dementia remain uncertain. This study was to investigate their potential associations. METHODS: A retrospective cohort study was conducted using the Clinical Practice Research Datalink. Patients with first-ever stroke but no prior dementia were followed up for 10 years. Cox regression was used to examine the association of baseline LDL-C, HDL-C and triglycerides with post-stroke dementia. RESULTS: Amongst 63,959 stroke patients, 15,879 had complete baseline data and were included in our main analysis. 10.8% developed dementia during a median of 4.6 years of follow-up. The adjusted hazard ratio of dementia for LDL-C (per log mmol/l increase) was 1.29 (95% confidence interval [CI] 1.14-1.47), with a linear increasing trend (p trend <0.001). The counterpart for triglycerides was 0.79 (95% CI 0.69-0.89), with a linear decreasing trend (p trend <0.001). For HDL-C, there was no association with dementia (adjusted hazard ratio 0.89, 95% CI 0.74-1.08) or a linear trend (p trend = 0.22). CONCLUSIONS: Blood lipids may affect the risk of post-stroke dementia in different ways, with higher risk associated with LDL-C, lower risk associated with triglycerides, and no association with HDL-C.