The aim of this study was to compare patterns of 24-hour ambulatory blood pressure between passive-smoking and non-smoking children. Subjects were 100 healthy children divided in 2 groups: passive smokers (72 children) and non-smokers (28 children). Children underwent 24-hour ambulatory blood pressure monitoring (ABPM). On the basis of ABPM results following daytime and night-time parameters were calculated for systolic blood pressure (SBP) and diastolic blood pressure (DBP): mean blood pressure (BP) value, BP load, BP variability magnitude, 24-hour blood pressure profile. The results were compared between passive smokers and non-smokers with t-Student test. Results with p < 0.05 were considered statistically significant. Smokers did not differ from non-smokers in mean daytime and night-time BP values. Daytime BP load, BP variability and 24-hour SBP profile were statistically higher in passive smokers, while night-time values of these parameters and DBP profile did not differ significantly. ABPM may be useful in detecting differences in BP characteristics of passive smoking and non-smoking children. Higher BP load and BP variability in smoking children may be early manifestations of BP regulation disorder, which might be helpful in early screening. Passive smoking may be a risk factor of hypertension.