Objectives: Intravenous (IV) fluid therapy is often needed in patients with the malignant disease during IV chemotherapy. The aim of our study is to evaluate the volume status of cancer patients treated with IV chemotherapy andstandard fluid therapy by using body composition monitor (BCM) measurements. Methods: Thirty chemotherapy cycles of the 30 cancer patients were evaluated. Patients had solid tumors (10.7%) andlymphoproliferative disease (89.3%). Biochemical and hematological parameters and fluid status by using BCM weremeasured on the 1st and fifth days of chemotherapy cycles. Results: Hypovolemia or hypervolemia were found both at baseline and 5. day during IV fluid and chemotherapy incancer patients (1.057±1.68 and 0.78±1.63 p>0.05 respectively). Also according to baseline, serum levels of Na, K, Ca,and body weight were decreased (p<0.04 for all), and CRP increased (p<0.02) on the 5th day. Conclusion: BCM measurements for fluid status revealed hypo/hypervolemia both at baseline and the 5. Day duringchemotherapy. Interestingly at 5.day serum CRP level increased and serum levels of Na, K, Ca decreased. So that technical assessment of volume status during IV chemotherapy and fluid therapy may reduce the risk of fluid and electrolytedisorders and inflammation.