OBJECTIVE: Chronic venous disease (CVD) and knee osteoarthritis (KOA) are two common diseases in the elderly. Both share common risk factors, such as age, sex, and obe-sity, and are believed to be associated with in-flammatory conditions and venous stasis. How-ever, studies of the association between CVD and KOA are limited, especially in the elderly. To investigate the association between CVD and KOA and their effects on pain and function-al status in the elderly at the Rheumatolo-gy Clinic of University Medical Center Ho Chi Minh City (HCMC).PATIENTS AND METHODS: This cross-sec-tional study included 222 elderly patients (aged >= 60 years) at the Rheumatology Clinic of Univer-sity Medical Center HCMC from December 2019 to June 2020, including 167 with and 55 with-out KOA. Patient data were collected for both groups, including demographics, symptoms, clinical signs, and diagnostic tests for KOA and CVD, including knee radiographs and duplex scanning of the lower extremity veins. RESULTS: CVD was a common comorbidity among elderly patients with KOA (73.65% vs. 58.18%; p = 0.030). CVD symptoms did not dif-fer significantly between patients with and with-out KOA. After adjusting for age, sex, body mass index, and some comorbid conditions, the differ-ences in CVD incidence between the groups re-mained significant (odds ratio = 2.46, 95% confi-dence interval: 1.20-5.06; p = 0.014). Visual Ana-log Scale and Western Ontario and McMaster Uni-versities Osteoarthritis Index pain scores were higher in elderly patients with KOA and CVD.CONCLUSIONS: CVD is common in elderly patients with KOA. While age, sex, and weight are risk factors for both conditions, there is an independent association between them. Pa-tients comorbid with KOA and CVD have more pain and limited functional status.