BACKGROUND: 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. METHODS: We conducted a retrospective cohort study using Clinical Practice Research Datalink. Patients with first-ever stroke but no prior dementia were followed up to 10 years. We used Cox regression to examine association of baseline LDL-C, HDL-C and triglycerides with post-stroke dementia. RESULTS: Among 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-year follow-up. The adjusted hazard ratio (aHR) 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 (aHR 0.89, 95%CI 0.74-1.08) or 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.