This study compared the long-term reproducibility of home blood pressure (BP) in comparison with office BP in children and adolescents. Forty-eight subjects (27 boys, mean age 11.3+/-3.1 (s.d.) years) recruited from the Arsakeion school study because of elevated office and/or home BP were assessed with office (1 visit, mercury sphygmomanometer) and home BP measurements (3 days, electronic devices) in two assessments 17+/-4.9 months apart (range 10-26 months). Home and office BP were compared on the basis of the following criteria: (a) s.d. of mean BP; (b) s.d. of differences; (c) variation coefficient (CV); (d) concordance correlation coefficient (CCC); (e) test-retest correlations; (f) correlation with ambulatory BP. (a) The s.d. of mean home BP was lower than that of office BP in both the initial (home BP 9.1/7.1 mm Hg, systolic/diastolic; office BP 13.1/8.0 mm Hg) and the second assessment (9.2/6.0 and 14.9/11.5 respectively). (b) The s.d. of differences was lower for home BP (8.3/6.5 mm Hg, systolic/diastolic) than for office BP (13.9/10.7 mm Hg). (c) The CV of home BP (5.3/6.6, systolic/diastolic) was lower than that of office BP (8.2/10.9). (d) The CCC of home BP (0.54/0.50, systolic/diastolic) was higher than that of office BP (0.51/0.41). (e) Test-retest correlations were closer for home BP (r=0.58/0.52, systolic/diastolic) than for office BP (0.51/0.44). (f) Awake ambulatory BP was more closely associated with home (r=0.77/0.40, systolic/diastolic) than with office BP (0.65/0.24). These data suggest that in children and adolescents the long-term reproducibility of home BP is superior to that of office measurements.