We aimed to investigate the prevalence of hyperhomocysteinaemia (total plasma homocysteine (tHcy) >= 10 mu mol/l) and its major determinants in rural Chinese hypertensive patients. A cross-sectional investigation was carried out in Lianyungang of Jiangsu province, China. This analysis included 13 946 hypertensive adults. The prevalence of hyperhomocysteinaemia was 51.6% (42.7% in women and 65.6% in men). The OR of hyperhomocysteinaemia were 1.52 (95% CI 1.39, 1.67) and 2.32 (95% CI 2.07, 2.61) for participants aged 55-65 and 65-75 v. 45-55 years; 1.27 (95% CI 1.18, 1.37) for participants with a BMI >= 25 v. <25 kg/m(2); 1.14 (95% CI 1.06, 1.23) for participants with v. without antihypertensive treatment; 1.09 (95% CI 1.00, 1.18) for residents inland v. coastal; 0.89 (95% CI 0.82, 0.97) and 0.83 (95% CI 0.74, 0.92) for participants with moderate and high v. low physical activity levels; 1.54 (95% CI 1.41, 1.68) and 2.47 (95% CI 2.17, 2.81) for participants with a glomerular filtration rate 60-90 and <60 v. >= 90 ml/min per 1.73 m(2); and 1.20 (95% CI 1.07, 1.35) and 3.81 (95% CI 3.33, 4.36) for participants with CT and TT v. CC genotype at methylenetetrahydrofolate reductase 677C. T polymorphism, respectively. Furthermore, higher tHcy concentrations were observed in smokers of both sexes (men: geometric mean 12.1 (interquartile range (IQR) 9.2-14.5) v. 11.9 (IQR 9.3-14.0) mu mol/l, P=0.005; women: geometric mean 10.3 (IQR 8.3-13.0) v. 9.6 (IQR 7.8-11.6) mu mol/l, P = 0.010), and only in males with hypertension grade 3 (v. grade 1 or controlled blood pressure) (geometric mean 12.1 (IQR 9.2-14.4) v. 11.7 (IQR 9.2-14.0), P = 0.016) and in male non-drinkers (yes v. no) (geometric mean 12.3 (IQR 9.4-14.8) v. 11.7 (IQR 9.1-13.9), P = 0.014). In conclusion, there was a high prevalence of hyperhomocysteinaemia in Chinese hypertensive adults, particularly in the inlanders, who may benefit greatly from tHcy-lowering strategies, such as folic acid supplementation and lifestyle change.