Abstract Background Hypertension is a major risk factor of global disease burden, but treatment goals are often not met. A subset of individuals with hypertension is affected by treatment-resistant hypertension (RHTN), and they suffer from increased cardiovascular morbidity and mortality. Early identification of individuals at risk of RHTN could lead to more efficient antihypertensive drug treatment. Purpose The aim of this study was to investigate whether polygenic risk scores (PRS) for systolic (SBP) and diastolic blood pressure (DBP) predict RHTN in individuals with or without type 1 diabetes (T1D). Methods We performed association analyses between PRSs and RHTN in two Finnish cohorts: The Finnish Diabetic Nephropathy Study (FinnDiane) and the Finnish individuals of the LIFE Study (LIFE-Fin). FinnDiane is an ongoing, observational nationwide study aiming to identify genetic and clinical risk factors for complications of T1D. We included data from 778 adults (476 with RHTN and 302 with controlled hypertension). LIFE is a randomized, double-blind study evaluating long-term effects of losartan compared with atenolol in patients with signs of left ventricular hypertrophy. We used SBP and DBP data from 378 Finnish individuals (173 with RHTN and 205 with controlled hypertension) at the four-year visit of the study. In FinnDiane, RHTN was defined as SBP ≥130 or DBP ≥85 mmHg and the use of three or more antihypertensive drugs, or SBP <130 and DBP <85 mmHg and the use of four or more antihypertensive drugs. In LIFE-Fin, RHTN was defined as SBP ≥140 or DBP ≥90 mmHg and the use of three or more antihypertensive drugs. Controlled hypertension was defined as the use of three or fewer antihypertensive drugs and SBP <130 and DBP <85 mmHg in FinnDiane, and as SBP <140 and DBP <90 mmHg in LIFE-Fin. We calculated a PRS for each participant using genome-wide association study data for 1,098,015 genetic variants; the variant-specific data were derived from UK Biobank based PRS-CS-method computed PRSs (1). Results We observed significant associations of SBP and DBP PRSs with RHTN in FinnDiane (OR 1.56 [1.30; 1.87], P = 1.8e-6, and OR 1.25 [1.04; 1.50], P = 0.02, per one-SD increase of the PRS value) when adjusted for age, sex, estimated glomerular filtration rate and body mass index. The association between SBP PRS and RHTN remained significant when T1D individuals with or without albuminuria were analysed separately. Neither SBP nor DBP PRSs were significantly associated with RHTN in LIFE-Fin. Conclusion Higher SBP PRSs associate with higher risk of RHTN in individuals with T1D, with or without albuminuria, but not in nondiabetic individuals with hypertension. It remains to be investigated whether general blood pressure genetics contribute to RHTN in the general population.