Classification of hypertensive subjects according to different blood pressure patterns : i.e sustained vs isolated clinic hypertension (ICH) , dipping vs non dipping is now regarded as a useful mean for a more precise individual risk stratification and therapeutic making decisions. However, this subdivision is routinely based on a single ambulatory blood pressure monitoring (ABPM), despite the well-known day-to-day variability in blood pressure due to variations in mental, physical and environmental stimuli. In this short review we have tried to answer the following question : how reliable is the classification of non-dipping and ICH pattern based on single 24-h ABPM recording? Data from the recent literature clearly indicate that these categorizations in non diabetic mild to moderate hypertensive patients on the basis of a single ABPM are highly unreliable , as a large fraction of subjects (20-50%) classified in these categories at the first ABPM, do not confirm the same BP pattern during a second ABPM. Thus, these findings support the idea that a more reliable classification of patients according to dipping/nondipping status or ICH vs sustained hypertension should be performed by repeating a second ABPM within a short-term period.