Introduction: Intraperitoneal volume (IPV) should be individualized and aimed to maintain an intraperitoneal pressure (IPP) lower than 17 cm H<sub>2</sub>O. IPP is very variable, given its relation with body size. However, it is not yet fully understood which anthropometric variable mostly affects IPP and the relation between IPP and organomegaly in polycystic kidney disease (PKD) patients is not known. Objectives: The aim of the present study was to analyse the relation between antropometric variables and IPP in a large cohort of peritoneal dialysis (PD) patients and to identify if a relation between nephromegaly and IPP exists in PKD patients. Methods: IPP was measured in PD patients and data was retrospectively collected. In PKD patients, total kidney volumes were measured in CT scans, and normalized with height (hTKV). Results: Seventy-seven patients were included in the study, 18% affected by PKD. Mean IPP was 14.9 ± 2.9 cm H<sub>2</sub>O and it showed significant positive correlation with body mass index (BMI; ρ = 0.42, p < 0.001). No correlation was found between IPP and absolute IPV; conversely, IPP has a significant inverse correlation with IPV normalized with BMI and body surface area ( ρ –0.38, p = 0.001 and ρ –0.25, p = 0.02, respectively). Patients with IPP >17 cm H<sub>2</sub>O have significant larger BMI and lower IPV/BMI compared to those with IPP <17 cm H<sub>2</sub>O (29 ± 3.6 vs. 26 ± 4 kg/m<sup>2</sup>, p < 0.05 and 97 ± 15.5 vs. 109 ± 22 mL/kg/m<sup>2</sup>, p < 0.05). PKD patients have a wide variability in hTKV (range 645–3,787 mL/m<sup>2</sup>) and it showed a significant correlation with IPP/IPV ( ρ = 0.6, p < 0.05). Conclusions: Patients with larger BMI have greater IPP, irrespectively to IPV. In PKD patients, hTKV correlate with IPP/IPV ratio. However, given the wide range of distribution of hTKV, increased IPP cannot be presumed because of pre-existing polycystic kidney, but need to be quantified.