The aim of this study was to focus on the relationship among the associated genotypes of G (8002) A and -3A/-4A endothelin-1 (ET-1) gene polymorphisms and some clinical and/or biochemical parameters in Czech (Caucasian) patients with chronic heart failure. Included in the study were 103 patients with chronic heart failure (functional classes NYHA II-IV, ejection fraction < 40%). The ET-1 gene polymorphisms were detected by polymerase chain reaction (PCR) and restriction fragment length polymorphism methods. A significant decrease in the ET-1-associated genotype AG3A4A number (double heterozygote) was observed in CHF patients with plasma big endothelin levels above 0.7 pmol/L compared to those with levels below 0.7 pmol/L (OR = 0.19; 95% confidence interval = 0.06-0.57; P = 0.005; Pcorr = 0.03). We found a significant decrease in the AG3A4A genotype number in the other groups compared to the group of patients with both big endothelin and endothelin-1 levels under 0.7 pmol/L (OR = 0.22; 95% confidence interval = 0.07-0.79; P = 0.02). The double heterozygote variants of two ET-1 gene polymorphisms were associated with significantly less risk for chronic heart failure with higher levels of big endothelin.