The main purpose of the study is to acquire useful information on nephrolithiasis in Italy, given the recent increase in its prevalence. The analysis was based on data from sample surveys of the Italian population carried out in 1983 and 1993-1994 as well as on data obtained from medical records of patients treated at the ASTIF in Fiuggi. An increase in the prevalence of the disease from 11.7 to 17.2 out of 1,000 inhabitants has been observed over the last 10 years; most patients are men and elderly, and the highest frequency is in southern and the lowest in northern Italy. The results of the study confirm the hereditary predisposition, since nephrolithiasis is very common among patients' parents (22.5%) and siblings (14.1%). The patients eat more meat than others and are often overweight or obese; the latter represent 18% of these patients and 11% of the general population.