BACKGROUND: It is estimated that, in Italy, 12 000-18 000 (11-13% of 130 000) HIV-infected subjects are not aware of their serostatus. People in this condition may visit the healthcare system multiple times without being diagnosed. If tested on one of these occasions, they could modify their high-risk behaviours and benefit from treatment, factors that reduce HIV transmission. In Italy, no data on HIV testing in the general population are available so far and little is known on the relationship between socioeconomic determinants (at individual and neighbourhood levels) and testing uptake. METHODS: A large anonymous survey was performed in 2012-2014 on more than 10 000 individuals 18-59 years old who underwent 21 public ambulatories in Rome to determine the proportion of subjects tested for HIV and factors related to testing uptake. Subjects' socio-demographic characteristics, sexual orientation, number of sexual partners, HIV risk behaviour, HIV testing uptake were collected by a self-administered questionnaire. Level of area deprivation was measured at the postal code level by the index of social disadvantage (ISD). Multilevel Poisson regressions were carried out to take heterogeneity between clusters (post code and clinics) into account. RESULTS: Among people participating in the study, 58.1% of subjects self-reported to have been tested at least once for HIV. Those who had one high risk behaviour for HIV-infection were 11% more likely to test than those not reporting any, and subjects who had had a STI (sexually-transmitted-infection) in the past were 12% more likely to test than those who had not had a STI. However only 44% (54% among subjects aged 18-35 years) of those with self-reported risks of contracting HIV had been tested at least once in life. This percentage increases, as expected, with the level of education, but, even so, about 40% of university educated subjects self-reporting risks of contracting HIV had never undergone an HIV test. CONCLUSIONS: This study highlights that, while the percentage of subjects tested is even higher than observed in other western nations, only 44% of subjects, self-reporting risks of contracting HIV, had tested at least once in life and about 40% of university educated subjects self reporting risks of contracting HIV had never tested.