ITACARE is a collaborative study on the survival of Italian cancer patients diagnosed in the period 1978-1989. The study involves 11 Italian population-based cancer registries (CRs) (Firenze, Forli-Ravenna, Genova, Latina, Modena, Parma, Ragusa, Torino, Varese, the childhood CR of Piedmont and the colorectal CR of Modena), and its principal aim is to identify and analyze possible differences between the areas covered by the CRs. This article describes the ITACARE database. Ten percent of the Italian population is covered by the participating CRs, most of which are located in the northern part of the country. All malignant cancer sites (classified by ICD-9) except skin cancers were included. For bladder cancers, papillomas and transitional cell tumours grade 1 and 2 were also included. Survival data on over 100,000 cases were collected. The principal information variables were sex, date of birth, diagnosis and end of follow-up, life status, ICD-9 code for tumour site, diagnosis modality (clinical, cytologic confirmation, histologic confirmation), ICD-0 morphology code, and tumour stage (grouped into broad categories). Follow-up is active in all registries. All cases were checked systematically for errors and inconsistencies, following which about 0.2% of cases were excluded from the analyses. The percentage of cases microscopically verified, which is an indicator of diagnostic accuracy and data reliability, was higher among patients under 65 years of age (90%), breast cancer patients (92%) and cases covered by the Varese, Torino and Forli-Ravenna CRs (more than 82%). The percentage of cases known by death certificate only (an indicator of the completeness and quality of registration) was about 3% of total cases and was higher among older patients (4%). Province-specific mortality, used to compute relative survival from cancer (i.e., survival adjusted for competing causes of death), varied according to period of diagnosis, sex and area: the highest mortality was among women of the Ragusa CR (Sicily) and men in northern CRs. Overall mortality decreased during the period, more markedly in the north and among women.