OBJECTIVES: To establish a conceptual model which relates osteoarthritis (OA) affectation, functional disability in daily activities, and Quality of Life (QoL).  METHODS: The present is an observational, cross-sectional, multicenter study. OA presence/absence, by location, was clinically recorded. Disability was assessed with the Health Assessment Questionnaire Disability Index (HAQ-DI), QoL through the EuroQoL-5D questionnaire. Descriptives were used for sociodemographic and clinical variables; relationship between OA, disability and QoL was estimated through Structural Equation Modeling (SEM). This multivariate analysis technique allows to hypothesize multiple relationships among latent, unobserved variables and tests the model with a equation system.  RESULTS: A total of 965 OA patients were included [mean age=64 years (SD=11); 75% women]. Mean body locations affected by OA was 2.81 (median=2; SD=1.613). The most frequently affected locations were knees (67% of the patients), lumbar (60%) and cervical (45%) spine. Regarding EuroQoL-5D, most patients reported not having severe problems in the five areas assessed. 'Other activities' (mean=1.172; SD=0.957) and 'reach' (mean=1.127; SD=0.912) were the HAQ-DI categories that showed higher disability.  The SEM presented OA, disability and QoL as latent, related variables. 92% of QoL was accounted for disability (R-squared=0.92). The global model that depicts OA as causing disability, and disability affecting QoL, has a marginal adjustment (CMIN/DF=5.42; RMR=0.026; RMSEA=0.069).  CONCLUSIONS: With the available data, the functional disability can account for the decrease in QoL. Theoretically, OA is strongly related with disability and QoL, but the model fails to fully explain this link. As statistical techniques need good measurement models to correctly estimate relationships, standard clinical records seem insufficient for this purpose. Additional valid measurements of OA affectation would be needed, to give evidence of its direct effect on disability and QoL.