Bologna, Florence, Genoa, Milan, Rome and Turin were the cities selected for the study. For each of the 15,266 respondents in 1980 and 15,874 respondents in 1982, a urine sample was tested for the presence of opiates. In addition, a questionnaire on demographic and socio-economic variables was completed. The study revealed 247 opiate cases in 1980, and 339 opiate cases in 1982. The number of opiate cases, demographic and socio-economic characteristics of respondents varied greatly from province to province. Unemployed respondents had a higher rate of opiate presence than any other occupational group. A methodology was used to estimate the number of opiate abuse cases that did not come to the attention of the authorities. Based on the methodology, it was estimated that there were 68,000 opiate users in 1980 and 92,000 in 1982 throughout the country. 5 tables, 3 references. (Author abstract modified)