End-stage renal disease (ESRD) and its treatment modules affect almost all organs and organ systems including vascular endothelium. It is well known that disturbance of vasoactive substances (nitric oxide - NO and endothelin-1 - ET-1) production appears in these patients. There is a small number of studies which investigated serum levels of NO and ET-1 in ESRD patients treated with continuous ambulatory peritoneal dialysis (CAPD). Therefore our study aimed to measure serum levels of NO and ET-1 in this population. This study included 23 ESRD patients (10 males and 13 females) treated with CAPD, mean age 55.8 ± 15.8 years. Mean duration of CAPD treatment in this group of patients was 3.4 ± 14.7 years. Besides this group of patients (CAPD), we included a second group which consisted of 30 healthy controls [14 males, 16 females, mean age 51.8 (±15.6) years]. Our results show significantly higher serum levels of NO in CAPD patients x ± SD = 19.09 ± 6.9) in comparison to the control group (x ± SD = 9.5 ± 1.9) (p < 0.05). There was no significant difference in serum levels of ET-1 between CAPD patients x ± SD = 7.3 ± 5.6) and the control group (x ± SD = 6.6 ± 4.2), (p > 0.05). From our results, we concluded that imbalance in production of vasoactive substances is present in CAPD patients. This imbalance can lead to disturbance in local blood flow control. These pathophysiological mechanisms can cause significant hemodynamic disturbance (hypertension) and atherosclerosis.