Objectives: Overhydration is a common finding in continuous ambulatory peritoneal dialysis (CAPD) patients. Body Composition Monitor (BCM) is a noninvasive method based on bioelectrical impedance spectroscopy to assess overhydration and body composition in dialysis patients. This study aims to determine whether there are differences in hydration and body composition parameters in CAPD patients with the dialysis fluid in the peritoneal cavity and after its drainage. Methods: A cross-sectional study enrolled 30 subjects undergoing CAPD at Fatmawati General Hospital, Jakarta, Indonesia. Examination was carried out with the Body Composition Monitor (Fresenius Medical Care, Germany) twice; when the peritoneal cavity is full of dialysate (D+) and when the peritoneal cavity is empty (D-). Parameter differences between D+ and D- were analyzed with paired t test and Wilcoxon nonparametric test. Results: Of the 30 research subjects, 56.7% of them were overhydrated above 2L. There were no differences in the values of overhydration, extracellular water, total body water, lean tissue mass, fat tissue mass, lean tissue index, and fat tissue index between D+ and D-. Conclusions: There were no differences in overhydration and body composition parameters between D+ and D- conditions. This suggests that BCM examination in CAPD patients can be performed without emptying the peritoneal cavity.