The M235T polymorphism of the angiotensinogen (ANG) gene, the I/D polymorphism of the angiotensin converting enzyme (ACE) gene, and the A1166C polymorphism of the angiotensin II type 1 receptor (AT1R) gene were identified in 70 patients with end-stage renal disease [20 pediatric ESRD, aged 14.9+/-3.1, years blood pressure (BP) 139+/-14/91+/-13 mmHg, 50 adult ESRD, aged 48.7+/-18.7 years, BP 149.1+/-24/96.9+/-12 mmHg], 35 with juvenile essential hypertension (JEHT, aged 14.4+/-2.7 years, 24-h mean BP 135.37+/-7.37/72.4+/-7.68 mmHg), 130 adult healthy normotensive controls (aged 34.9+/-8.1 years, BP 117.8+/-8.7/78.7+/-8.5 mmHg), and 20 pediatric controls (aged 13.2+/-1.2 years, BP 109+/-6.5/71+/-5.9 mmHg). The ACE gene polymorphism was determined by polymerase chain reaction and the ANG and AT1R gene polymorphisms by single-step LightCycler technology. The ACE gene distribution of the Hungarian controls did not differ from the results of the other Caucasian populations. In JEHT and pediatric ESRD patients, the MT genotype of ANG was more frequent than in controls (JEHT 80%, pediatric ESRD 74% versus controls 50%, P<0.02). The DD genotype of ACE was over-represented in pediatric ESRD compared with controls (ESRD 45% versus controls 22%, P<0.05). There was a non-significant increase in the CC genotype frequency of AT1R in adult patients with ESRD compared with controls. In conclusion, there was an increased frequency of the ACE DD genotype in pediatric ESRD, which could be a genetic risk factor for the development of ESRD. Furthermore, there was a significant increase in MT genotype frequency of ANG M235T polymorphism in pediatric ESRD and JEHT. The role of AT1R gene polymorphism needs further investigation.