OBJECTIVES: This study aimed to describe the prevalence of symptomatic knee and hip osteoarthritis (OA) and its course over time, as well as identify prognostic factors of OA course and determinants of costs and access to care in France in a patient cohort. METHODS: Subjects aged 40 to 75 years, with uni- or bilateral symptomatic hip and/or knee OA (ACR criteria), Kellgren and Lawrence (KL) stage 2 or greater, were recruited from a French national prevalence survey for the multicenter KHOALA cohort study. Data collected at baseline included sociodemographic and clinical data; WOMAC, IKS and Harris scores for pain and function; MAQ score for physical activity; functional comorbidity index; GHQ28 score for psychological status; and SF-36 (generic) and OAKHQOL (specific) scores for quality of life. Blood and urine samples were collected. RESULTS: Eight hundred and seventy-eight subjects were included, 222 with OA of the hip (mean age 61.2±8.8 years), 607 knee (mean age 62.0±8.5 years) and 49 both hip and knee (mean age 64.9±7.9 years). Mean body mass index was 26.9±4.5 for hip OA and 30.3±6.3 for knee OA. Hip and knee OA patients had 1.99 and 2.06 comorbidities, on average, respectively. Disease severity on X-rays for KL stages 2, 3 and 4 for hip OA was 69.8, 26.1 and 4.1%, respectively, and for knee OA, 44.5, 30.3, and 25.2%. As compared with population norms, age- and sex-standardized SF-36 scores were greatly decreased for both knee and hip OA in all dimensions, particularly physical and emotional dimensions. PERSPECTIVES: Patients will be followed up annually, alternately by mail and clinical visit. This cohort of representative patients with knee and hip OA will be an opportunity for future collaborative research.