Objective We compared the fluid volume parameters in women undergoing gynaecological surgery for benign and malignant conditions before and after surgery using bioelectrical impedance vectors. Study design A total of 181 patients were enrolled. In all, 89 patients had surgery for benign conditions and 92 patients underwent oncological procedures, including lymph node dissection, for malignant diseases. Bioelectrical impedance analysis (BIA) parameters were measured on the day of hospitalisation before any treatment and at 24 h and 1 month after the surgical intervention. The BIA parameters measured included extracellular water (ECW), intracellular water (ICW), and total body water (TBW). Results TBW increased significantly 1 month after surgery in all cases (p < 0,05 in both group). ECW was significantly higher (p < 0.05) and ICW was significantly lower (p < 0,05) in the malignant group than the benign group. Conclusion Radical gynaecological surgeries, including lymph node dissection, have a greater effect on body water distribution than surgeries performed for benign conditions.