OBJECTIVE:: Autonomic neuropathy (AN) may lead to impaired circadian blood pressure (BP) regulation, with concurrent diurnal orthostatic hypotension (OH) and nocturnal hypertension, detected by 24-hour ambulatory blood pressure monitoring (ABPM).ABPM may be a potential diagnostic tool to identify specific BP patterns in patients with AN.So the aim of our study was to identify the characteristic patterns of circadian blood pressure profile in a cohort of primary AN patients and to evaluate the interference of vasoactive medication or cardiovascular comorbidities on these specific circadian patterns. DESIGN AND METHOD:: ABPM of 110 patients with primary AN referring to Autonomic Unit of Torino from 1996 to 2015 were retrospectively reviewed. RESULTS:: 33% of the subjects were women and mean age was 68 ± 9.2 years; 66% had Parkinsonʼs disease, 16% multiple system atrophy, 16% pure autonomic failure, 2% other forms of primary AN (in particular 1 form of autoimmune AN e 2 forms of mixed primary and secondary AN).22% of the patients had a history of hypertension anteceding AN diagnosis; 38.2% of them were treated with vasoactive medications during ABPM (15.5% with anti-hypotensive, 17.3% with anti-hypertensive, 5.5% with both types of drugs)Mean daytime systolic and diastolic BP were within normal limits (121.2 ± 14.1/72.3 ± 8.3 mmHg) while mean nighttime systolic and diastolic BP (133.7 ± 19.6/76.5 ± 13 mmHg) were elevated.Nocturnal hypertension and a ’reverse dipping’ pattern were found in 80% of patients.Nighttime systolic and diastolic BP loads were 62.2 ± 33.6% e 53.2 ± 13.8%, respectively.64% of subjects had a high BP variability (defined as standard deviation of nighttime mean systolic BP > 11). Morning orthostatic hypotension and postprandial hypotension were found in 66% and 79% of patients, respectively.No significant differences regarding mean daytime and nighttime BP and circadian BP patterns were found between patients with and without vasoactive medications (both increasing and lowering BP). The same BP patterns (diurnal OH and reverse dipping) were also detected in patients with a previous history of hypertension. CONCLUSIONS:: ABPM may detect circadian BP alterations associated with AN also in subjects treated with anti-hypertensive or anti-hypotensive medications.