The aim of the study was to assess the existence of possible associations among frequent polymorphisms in angiotensinogen genes and some of the risk factors for essential hypertension, especially body mass index (BMI) and smoking. A total of 192 control subjects (aged 45.87 +/- 3.0 years) and 206 patients with the essential hypertension (aged 48.71 +/- 8.42 years) were compared at three angiotensinogen gene polymorphisms by considering BMI and smoking status. No significant differences in genotype and/or allelic distribution for either A (-6) G ATG, M235T or T174M polymorphisms between the hypertensive and control groups were proved. Significantly more hypertensives than control persons with BMI above 25 kg/m(2) were observed (P(corr) = 0.009), independently on sex distribution. A percentage of 44.6% of smokers in the control group vs 46.0% of smokers in the hypertensive groups were found. No significant difference in concurrence of BMI above 25 kg/m(2) and positive smoking status between control and hypertensive subjects was found. Statistically significant differences were found between control and hypertensive subjects when compared distributions of subjects with certain genotypes of the three examined polymorphisms considering BMI (P(corr) = 0.0002 for AA+AG of A (-6) G ATG, P(corr) = 0.01 for CC + CT of T(174)M ATG and P(corr) = 0.01 for MT + TT of M235T ATG). No functional relationship among obesity and the examined polymorphisms in vivo are known. We conclude that a different distribution of BMI could influence the results of analyses of angiotensinogen gene polymorphisms in essential hypertension-control studies.