VAP-1 (vascular adhesion protein-1) possesses semicarbazide-sensitive amine oxidase (SSAO) activity. It has also been found that serum VAP-1 was elevated in acute and chronic hyperglycemia and in patients with diabetes as well as in chronic kidney disease. Renalase, with possible monoamine oxidase activity, which breaks down catecholamines such as SSAO, is expressed in the endothelium as well as in the kidney. The aim of the study was to assess serum VAP-1 levels in peritoneally dialyzed (PD) patients and factors explaining its variability. This pilot study was performed on 25 peritoneally dialyzed patients, including 4 patients with type 2 diabetes. We found that the mean VAP-1 was significantly higher in chronic ambulatory peritoneal dialysis (CAPD) patients when compared to the control group (p<0.05). Dopamine was significantly lower in PD patients when compared to the healthy volunteers (p<0.05), whereas noradrenaline was significantly higher in PD patients relative to the healthy volunteers (p<0.01). There was a significant difference in the VAP-1 concentration in the group with and without residual renal function (p<0.05) as well as between 10 patients with hyperglycemia when compared to patients with normoglycemia (p<0.05). There was no effect of gender on the serum VAP-1 levels. In PD patients VAP-1 correlated with systolic blood pressure (r=-0.4, p<005), residual renal function (r=-0.62, p<0.05), and glucose (=0.54, p<0.05). We concluded that VAP-1, elevated in patients on PD, was predominantly dependent on residual kidney function and glucose level, factors both linked to endothelial damage and cardiovascular complications.