The Sentinel Panel of Districts (SPD) consists of 23 districts selected to provide nationally representative data on demographic and health indicators in Tanzania. The SPD has two arms: SAVVY and FBIS. SAVVY (SAmple Vital registration with Verbal autopsY) is a demographic surveillance system that provides nationally representative estimates of mortalities based on age, sex, residence and zone. SAVVY covers over 805 000 persons, or about 2% of the Tanzania mainland population, and uses repeat household census every 4-5 years, with ongoing reporting of births, deaths and causes of deaths. The FBIS (Facility-Based Information System) collects routine national health management information system data. These health service use data are collected monthly at all public and private health facilities in SPD districts, i.e. about 35% of all facilities in Mainland Tanzania. Both SAVVY and FBIS systems are capable of generating supplementary information from nested periodic surveys. Additional information about the design of the SPD is available online: access to some of SPD's aggregate data can be requested by sending an e-mail to [hmasanja@ihi.or.tz].