A prospective study on 1,482 adult members of 98 Utah pedigrees was carried out to determine which variables may be associated with an increased risk of hypertension incidence. After an average of 7 years of follow-up, 40 individuals had been placed on antihypertensive medications to lower blood pressure. Baseline study variables included anthropometrics, clinical chemistry measurements of blood and urine, socioeconomic and lifestyle variables, and detailed erythrocyte ion transport and concentration measurements. Age (relative risk of 4.28 for a 2 SD difference, p less than 0.0001) and baseline systolic and diastolic blood pressures (relative risks of 3.55 and 3.52, respectively, both p less than 0.0001) had the strongest associations with hypertension incidence. Controlling for age and baseline blood pressure, the following age- and sex-adjusted variables were associated with an increased risk of future hypertension (relative risks for a 2 SD difference, all p less than 0.10): family history of hypertension (2.35); height (1.97); body mass index (2.31); abdominal girth (2.66); subscapular, suprailiac, and triceps skinfold thicknesses (2.79, 2.52, and 2.28, respectively); percent ideal body weight (2.63); log triglyceride concentration (2.02); plasma uric acid (2.16); inorganic phosphate (0.50); and passive erythrocyte sodium permeability (1.59). The final model,which included all of the age- and sex-adjusted variables (p less than 0.10) in a backward elimination logistic regression analysis, consisted of age (4.78), systolic blood pressure (2.91), subscapular skinfold thickness (2.21), height (1.92), uric acid (2.06), inorganic phosphate (0.50), and family history of hypertension (1.82). None of the ion transport or concentration measurements ws associated with an increased risk of hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)