Background: Thalassemia is one of the most common genetic disorders worldwide that associated with defective hemoglobin-chain synthesis. Clinical manifestations are diverse, ranging from asymptomatic hypochromia and microcytosis to profound anemia. Aim of study: This study aimed to assess the relationship between knowledge of patients with thalassemia and their quality of life through: (1) Assessment of level of knowledge for adult patients suffering from thalassemia, (2) Assessment of quality of life among adult patients suffering from thalassemia. Research design: A descriptive exploratory research design was utilized to achieve the aim of the present study. Setting: The current study was carried out in general medicine department at El Fayoum university hospital. Subject: A purposive sample of 80 adult patients with thalassemia was included in this study. Tools of data collection: First tool: Patient interview questionnaire. Second tool: World Health Organization Quality of Life-BREF (WHOQOL-BREF) questionnaire. Results: The results of this study revealed that more than two thirds of patients had satisfactory level of knowledge regarding thalassemia, and more than three quarters of patients had poor quality of life. Conclusion: It was concluded that there was no statistical significance relation between total level of knowledge of patients with thalassemia and their quality of life. Recommendations: Regular follow up for patients with thalassemia to evaluate their health conditions and to detect complications early. Further studies are needed to assess factors affecting quality of life of patient with thalassemia. Keywords: Knowledge -Quality of Life -Thalassemia -Patients. Introduction:The term 'thalassemia' refers to a genetic blood disease. Thalassemia is the most prevalent inherited hemo-globinopathy that result from a decreased synthesis of alpha or beta chains of hemoglobin (Hb) (Bhurani et al., 2021).