We studied the prevalence of arterial hypertension and its associated risk factors in the urban population of León, State of Guanajuato. Using a cross sectional design we selected by home interview 1000 volunteers 16 to 70 years old from three socioeconomic levels. Forty seven of 468 males (10.0%) and 67 of 532 females (12.6%) were found with hypertension. Increased rates for women were significant (p < 0.01). The rates of hypertension increased slowly with age for men, but for women a sudden increase was found at 48 years of age, the mean age of menopause. At 50 years of age or older, the rate for hypertension was 22.3% for men and 41.7% for women (chi 2 = 7.27, p = 0.007). The multivariate study of factors associated with hypertension showed significance for age, body mass index and smoking habit for the total group and for men, but only age and body weight for women. No association was seen for alcoholism, life style and socioeconomy. A univariate analysis of menopause was strongly associated with hypertension (chi 2 = 46.8, p < 0.0001) and the relative risk for hypertension in menopausal women was 8.04 (7.56-9.73). We conclude that the frequency of hypertension in this urban population is similar to that found in other studies except for women over 50 years of age. Such excess risk of hypertension in this group may be explained by an increased frequency of obesity and an increment in sedentary habits which occur in our female population, and the possible participation of hormone deprivation.