A record linkage was carried out between the Italian Registry of AIDS and 19 Cancer Registries (CRs), which covered 23% of the Italian population, to estimate the overall cancer burden among persons with HIV or AIDS (PWHA) in Italy, according to various characteristics. Observed and expected numbers of cancer and standardised incidence ratios (SIRs) were assessed until 1998 in 12 104 PWHA aged 15-69 years, for a total of 60 421 person-years. Significantly increased SIRs were observed for Kaposi's sarcoma (KS, 1749-fold higher than the general population), non-Hodgkin's lymphomas (NHL, 352), and invasive cervical cancer (22). SIR was significantly elevated also for cancer of the anus (34), lung cancer (2.4), brain tumours (4.4), Hodgkin's disease (16), and leukaemias (5.3). The majority of lung and brain cancers were not histologically confirmed, and the possibility of misclassification with KS or NHL cannot be ruled out. The SIR for all non-AIDS-defining cancers was 2.2 in men and 2.5 in women. Intravenous drug users showed significantly more elevated SIRs for lung cancer (9.4), and brain tumours (6.7) than other transmission categories (SIR=1.4 and 2.3, respectively). This study confirmed increased SIRs for haemolymphopoietic neoplasms other than NHL in PWHA, although many-fold smaller than for NHL. An association with human papillomavirus-related cancers was also confirmed.