Introduction: There are limited studies on plate waste and satisfaction levels among adult patients receiving therapeutic diets in hospitals, particularly in the local context. Therefore, this study aimed to determine the percentage of plate waste and the level of satisfaction among adult patients receiving therapeutic diets, as well as the contributing factors. Methods: This cross-sectional study was conducted at a university hospital during lunch and dinner hours on eleven types of therapeutic diets. Food weighing and photography-assisted visual estimation by the Comstock scale were used to measure plate waste. Interviews were conducted with patients using the Acute Care Hospital Foodservice Patient Satisfaction Questionnaire (ACHFPSQ) to collect information about their satisfaction towards food quality and service. Results: Mean overall plate waste rate for 96 patients receiving therapeutic diets was 43.6% (40.0% for lunch, 47.3% for dinner), with the highest rate of wastage in a combined diet low in fat and salt. Overall score for patient satisfaction was 3.7 out of 5. Patients had higher satisfaction levels with staff and food service (4.0) compared to food quality (3.4). Food quality negatively contributed to the rate of plate waste in terms of taste (r=-0.107, p=0.035), presentation (r=-0.078, p=0.043), and texture (r=-0.052, p=0.020). Conclusion: Therapeutic diet plate waste among adult patients in this study was high and primarily attributable to food quality. Efforts to minimise therapeutic diet plate waste should be made by improving food quality for the best possible outcomes for patients.