Background: Hematopoietic stem cell transplantation involves the intravenous infusion of autologous or allogeneic stem cells to reestablish hematopoietic function in patients whose bone marrow or immune system is damaged. This study aimed to modify the fluid balance chart for nurses to monitor fluid volume disturbance in patients undergoing hematopoietic stem cell transplantation. Design: A prospective, single - centered research design was utilized in this study. Setting: The study was conducted at the Bone marrow transplantation unit at South – Egypt Cancer Institution. Subject: A purposive sample of 25 adult conscious patients undergoing stem cell transplant, from both sexes and age range between (20 – 65years).Tools: three tools were used; a structured interview questionnaire, modified fluid balance chart, and a fluid volume disturbance monitoring sheet. Results: There was a statistically significant difference between the modified and routine fluid charts regarding the mean amount of daily fluid balance (10750.00 ± 409 ml) and (8333. 63 ± 388 ml) respectively with (P.value = 0.001). Conclusion: modification of fluid balance chart has a great effect on accurate monitoring of the fluid intake, output, and fluid volume disturbances.