Background: Adherence is a dynamic, multidimensional process in which many factors play a part. So, nurses play an important role to informed Patient with all health information needed about the medical condition, to improve quality of life. Aim: This study aimed to assess factors affecting adherence to therapeutic regimens and it's association with knowledge level among patients with cardiac valve replacement. Design: A descriptive exploratory design was conducted to achieve aim of this study. Setting: the study was carried out in Cardiac Surgery Care Unite and Department at Benha University Hospitals and Heart Academy Hospital at Ain Shams University. Subjects: A Convenient sample of 60 patients admitted in previous mentioned setting. Tools: Three tools were used to collect the study data. Tool I: Patient's knowledge assessment questionnaire, Tool II: adherence scale, Tool III: Medical and socio-economic factors affecting adherence to therapeutic regimen. Results: 80% of studied patients had unsatisfactory level of knowledge. 65% of them had low level of adherence to therapeutic regimen, the study revealed that, 43% of them had highly affecting with social factors, while, 57% of them had low affecting with physical factors. Conclusion: There were high percentages of patients had unsatisfactory level of knowledge and low level of adherence in the light of presence of affecting factors. finally, there was a positive correlation between total adherence and total knowledge. Recommendations: Establishment of patients' educational centers in hospitals equipped by suitable related materials, medias and audio-visual aids for teaching all patients with cardiac valve replacement how to cope with their health condition.