['High normal blood pressure (HNBP), i.e. blood pressure (BP) > or = 130/85 mmHg and <140/90 mmHg, is an important predictor of progression to established hypertension.', 'The purpose of this retrospective study was the evaluation of the predictive value of ambulatory blood pressure monitoring (ABPM) for the development of drug-treated hypertension in subjects with HNBP and other risk factors.', 'We studied 127 subjects (69 M, 58 F, age 50 +/- 14 years): 59 subjects had normal BP (NBP: < 130/85 mmHg), 68 subjects had systolic and/or diastolic HNBP. All the subjects underwent ABPM. There were 21/68 (30.9%) subjects in the HNBP group vs. 1/59 (1.7%) in the NBP group with an elevated (>135/85 mmHg) daytime ambulatory blood pressure (ABP) (p < 0.01).', 'After an average follow-up of 103 +/- 28 months, 27 subjects (39.7%) in the HNBP group and 4 subjects (6.8%) in the NBP group developed drug-treated hypertension (p < 0.01). An elevated daytime ABP correctly predicted development of drug-treated hypertension in 17/21 subjects (81%) of the HNBP group and in the only subject of the NBP group. Development of drug-treated hypertension was associated with higher office and ambulatory BP (p < 0.01) and pulse pressures (p < 0.05), longer follow-up (p < 0.05) and higher prevalence of hypercholesterolaemia and smoking (p < 0.01).'] Does ambulatory monitoring predict development of drug-treated hypertension in subjects with high normal blood pressure?