Background: Cancer patients undergoing chemotherapy commonly experience oral problems. Implementing an evidence-based care bundle plays a vital role in effectively managing these mouth problems and improving patients’ quality of life. Aim: To evaluate the effect of care bundle on managing mouth problems among cancer patients undergoing chemotherapy. Design: Quasi experimental pretest and posttest research design was used was used. Setting: The study was conducted in medical oncology and nuclear medicine unit at Benha University Hospital, Benha, Egypt. Subjects: A purposive sample of 100 adult patients with age ranging from 20-60 years old, from both genders undergoing chemotherapy. Tools: Four tools were used; tool (I): A structured interviewing questionnaire, it involved the patients' personal data, medical history and patients' knowledge assessment. Tool (II): Patients' practice observational checklist. Tool (III): Thirst Intensity Scale. Tool (IV): Oral Health Assessment Tool (OHAT. Results: Findings revealed that patients with satisfactory knowledge increased from 11% pre-intervention to 73% immediately after and 69% at one month (p=0.016, 0.033). Similarly, good practice levels improved from 0% pre-intervention to 68% immediately and 63% at one month (p=0.002, 0.010). Oral health condition also showed marked improvement, with no patients having a healthy mouth pre-intervention compared to 23% after two days and 43% after one month (p