Blood pressure screening was carried out on a university campus to identify early hypertension or high-normal BP in young adults. Compared with normotensive control subjects of a similar age, drawn from the same population, persons identified as being at the upper end of the BP distribution had significantly increased levels of sodium-lithium counter-transport. This difference persisted when other potential confounding variables, eg, overweight, sex, ethnicity, sodium excretion, and age, were taken into account. A positive family history was associated with slightly higher levels of sodium-lithium countertransport, although the effect could be explained by higher present levels of BP. These data suggest that abnormalities of cation transport are present early in the course of the development of hypertension. Measurement of transport levels may provide an estimate of risk of hypertension and allow identification of susceptible persons.