Chemotherapy is a type of cancer treatment that use one or more anti-cancer drugs as part of a standardized chemotherapy regimen. The study aimed to evaluate effect of oral care and relaxation technique on gastrointestinal tract problems of patients undergoing chemotherapy. Research design: A quasi-experimental design was utilized to conduct this study. Setting: The study was conducted at the Chemotherapy Unit, Benha University Hospital in Benha City. Sample: Systematic random sample was used, it included (100) patients undergoing chemotherapy. Three tools were used: I: A structured interviewing questionnaire to assess; a) Socio-demographic characteristics of studied patients, b) Medical history of studied patients, c) Knowledge of studied patients regarding chemotherapy. II: Observational checklist which consists of two parts to observe a) Oral care protocol, b) Progressive relaxation technique. III: Scale to measure gastrointestinal tract problems of patients undergoing chemotherapy. Results: 53.0% of the studied patients had good knowledge while, 63.0% of the studied patients had satisfactory practices and 53.0%of the studied patients had mild gastrointestinal tract problems post implementation of intervention. There was positive statistically significant correlation between the studied patients' total knowledge, total practices and total severity of gastrointestinal tract problems post implementation of intervention Conclusion: The nursing intervention succeeded to improve knowledge, practices and severity of gastrointestinal tract problems of the studied patients undergoing chemotherapy. Recommendations: Continuous application of nursing intervention for patients undergoing chemotherapy to enhance patients' knowledge, practices and severity of gastrointestinal tract problems.