Hyperhomocysteinemia is a risk factor for cardiovascular disease. C677T mutation at the MTHFR gene and deficiencies of folic acid and vitamin B-12 may account for elevation of total homocysteine (tHcy). Ninety Brazilian Parkatêjê Indians (90.0% of the population without admixture, aged > or = 20 years) were studied. Hyperhomocysteinemia was observed in 26.7% of the Indians. No case of vitamin B-12 deficiency was detected. Folic acid deficiency was found in 43.3% of the subjects. Rates of mutated allele 677T and TT genotype were 40.7% and 14.0%, respectively. Prevalence of hypertension, dyslipidemia, smoking, WHR > or = 0.9, BMI > or = 25 kg/m2 and chronic alcohol use were 4.4%, 44.4%, 25.6%, 72.2%, 67.8%, and 0.0%, respectively. All creatinine values were normal. Natural logarithmic (ln) tHcy showed no correlation with age, but was positively correlated with systolic (r = 0.22) and diastolic (r = 0.21) blood pressure and triglycerides (r = 0.39) and inversely correlated with folic acid (r = -0.40) adjusted for age and sex. Total homocysteine (tHcy) was higher among TT genotype (P < .001). The multiple linear regression model, containing variables for sex, folic acid, TT genotype, and triglycerides, explained 50.0% of the variation of the ln tHcy. In summary, high rates of cardiovascular risk factors were discovered. C667T mutation and folic acid deficiency can explain, at least in part, the observed hyperhomocysteinemia.