OBJECTIVE: To establish the acceptability and tolerance of ambulatory blood pressure monitoring (ABPM). METHODS: A two-part questionnaire was completed by the doctor; one part before ABPM and the second after the recording. The pre-recording data concern the demographic data of the patient: previous illness, symptoms, reaction of the patient, anthropometric data, treatment details and the reason for ABPM. The second part of the questionnaire records the type of monitor used, the conditions of the recording and any difficulties for, or adverse effects on, the patient. SUBJECTS: Six hundred and seventy-two patients considered hypertension by World Health Organization criteria (diastolic blood blood pressure >/=90 mmHg, systolic blood pressure >/=140 mmHg), were considered for the first descriptive part of the study; a total of 654 patients were considered for the second part related to tolerance; 18 patients refused to reply to the questions concerning the second questionnaire. The general characteristics of the population were as follows: 345 men (51.5%), 327 women (48.5%) and mean age 54+/- 15 years. RESULTS: The devices used were SpaceLabs (63%), Novacor (19.3%), Nippon Collin (6.3%) and other machines (11.2%). The difficulties caused by the machine were classified as 'nul', 'moderate' or 'important'. The levels of difficulty defined as 'important' were 32% related to the cuff, 14% to the awkwardness of the machine and 6% to the noise of the monitor. Difficulty in driving was reported in 9% of cases and difficulty related to comments by colleagues in 6%. Analysis during sleep hindered sleep in 55%, with a very disturbed sleep pattern (more than three reported awakenings) in 14% of cases. Regression analysis allowed examination of the links among the different variables, taking into account the type of machine or the profile of the subject. Thus, it was possible to differentiate among the elements that could influence or predict intolerance. CONCLUSION: Recording-related problems are not negligible but can be reduced by an approach oriented towards each individual patients, taking into account specific information for particular circumstances.