Introduction: G-CSF producing tumors often cause various symptoms at the end of life, such as fever, fatigue, and fluid retention as a result of high cytokine status. Case: The patient was an 80-year-old woman. She was referred to our hospital because of anorexia and urine volume reduction. After a detailed examination, she was diagnosed with duodenal cancer. Although she decided not to receive anticancer treatment because of her old age and poor general condition, she felt a great distress with abdominal distension by large ascites. Furthermore, peripheral blood smear examination showed remarkably increased levels of normal neutrophils. We suspected G-CSF producing tumor and, hence, dexamethasone administration was initiated to suppress cytokine release. As a result, renal dysfunction and urine volume were improved, and ascites accumulation was not observed again since initial paracentesis. The number of neutrophils also declined, and the patient was in a good condition, even though it lasted for a short time. Conclusion: In patients with high cytokine status caused by G-CSF producing tumor, steroids may be useful for pain relief.