The diffusion of ambulatory monitoring (AM) in Italy was evaluated by a questionnaire sent to 102 centers known to be active in this field. The 70 replays obtained constitute this report. In Italy the first center for AM was activated in 1970, thereafter many other new centers started with the maximal increase between 1978 and 1983. During 1985 these centers performed 36223 examinations (mean 517) with a great variability in the number of examinations performed per year: 11 centers performed greater than 1000 examinations a yr, 21 greater than 500 less than 1000 and 38 less than 500. This variability was independent by the number of recorders each center have (on average 4.78 per center) and by the number of personnel involved in the activity. Waiting list resulted to be 25 days on average (1.90) and 4.7 days were needed for the replay (1.20). The main complain resulted to be the difficulty to obtain in short period of time technical assistance. In the second part of the questionnaire more clinical questions were asked. AM resulted to be required the most for arrhythmias and ischemic heart disease whereas atypical chest pain, palpitations and lipothymia events were considered to be the major reasons for a negative examination. In conclusion our data allow to identify the clinical relevance of AM in Italy and its major applicants.