Objectives: Neuropsychiatric symptoms and anosognosia are known to influence the perceived quality of life of patients (QoL-p) with Alzheimer's disease (AD). This study analysed their impact on patient and caregiver ratings of QoL-p and how these ratings changed in relation to the severity of dementia. Methods: A baseline sample of 221 patients and caregivers was followed up over 24 months. Instruments: Neuropsychiatric Inventory (NPI), Anosognosia Questionnaire-Dementia (AQ-D), Quality of Life-Alzheimer's Disease (QoL-AD), and the Global Deterioration Scale (GDS). Longitudinal data were analysed using generalized linear models. Results: In the multivariate analysis, greater anosognosia was always associated with higher ratings of QoL-p among patients, especially at 24 months (p < 0.001), and with more negative ratings among caregivers, especially at baseline (p < 0.001). A higher total NPI score was associated with a more negative rating of QoL-p among caregivers (p < 0.001), and it also had a smaller negative effect on patients' self-ratings (p = 0.001). The neuropsychiatric symptoms (NPI) associated with a more negative view of QoL-p were depression, for patients' self-ratings, and apathy and agitation for caregiver ratings. The discrepancy between patient and caregiver ratings increased in line with the severity of dementia. Conclusion: Neuropsychiatric symptoms and anosognosia have differential effects on patient and caregiver ratings of the quality of life of patients with Alzheimer's disease. Key words: Alzheimer's disease, quality of life, anosognosia, neuropsychiatric symptoms, caregivers, patients.