The aim of the present study was to perform a meta-analysis of published studies in an attempt to determine the mean and range of normal ambulatory blood pressure. Twenty-two studies, including a total of 2638 subjects, were reviewed. Most studies were compatible with a mean 24-h ambulatory pressure in the range of 115/70-120/75 mmHg, a mean daytime pressure of 120/75-125/80 mmHg and a mean night-time pressure of 105/60-110/65 mmHg. With weighting for the number of subjects included in the individual studies, the 24-h ambulatory pressure averaged 117/72 mmHg, the daytime pressure 122/77 mmHg and the night-time pressure 106/64 mmHg. The night: day pressure ratio averaged 0.87 for systolic and 0.83 for diastolic pressure, ranging from 0.79 to 0.92 and from 0.75 to 0.90, respectively, across the individual studies. With the mean +/- 2 standard deviation studies taken as normal, the range of normality averaged 97/57-137/87 mmHg over 24 h, 101/62-143/91 mmHg for the daytime pressure and 86/48-127/79 mmHg for the night-time pressure.