The relationships between plasma digoxin-like immunoreactivity (DLS) and atrial natriuretic peptide (ANP) were investigated in 10 young essential hypertensives (mean age 22 +/- 2 years) and in 10 normotensives. In young hypertensives, plasma DLS and ANP were at an average level of 31.2 +/- 8 pg/ml and 56.7 +/- 20 pg/ml respectively, showing a significant correlation (r = 0.66; p less than 0.05). In normal subjects plasma DLS and ANP were at an average level of 19.1 +/- 8 pg/ml and 37.6 +/- 16.7 pg/ml respectively (n.s.). Plasma DLS and ANP were higher in hypertensives than in normotensives (p less than 0.01). In conclusion, DLS and ANP appear to have a similar behaviour, possibly due to their modulation by common stimuli.