The 1993-94 Bangladesh Demographic and Health Survey (DHS) reported substantial declines in vital rates, especially the fertility rate, which needed confirmation. The demographic database of the International Center for Diarrheal Disease Research, Bangladesh (ICDDR,B) contains the birth and death records for 200,000 people whose households have been visited every 2 weeks since 1966. In addition, the system kept records on the pregnancy and contraceptive use status of women of reproductive age since 1977. A validation study was conducted, which entailed the comparison of fertility and infant mortality rates from a special DHS survey conducted in the Matlab treatment area in 1994, with rates obtained by the Demographic Surveillance System (DSS) over the 5 years prior to the survey and also the comparison of the current contraceptive use rate. The records of 2628 women were examined. The Matlab DHS was found to be accurate in estimating fertility both in the treatment and comparison areas. The Matlab DHS infant mortality rates for the 5 years prior to the survey were also consistent with the estimates derived from the DSS. However, the Matlab DHS seemed to have underestimated contraceptive prevalence, which underestimate was substantial for modern temporary methods, especially pills and injectables. Since contraceptive prevalence may also be higher at the national level as a result of this, the total fertility rate for Bangladesh of 3.4 children/woman may be plausible. Although the Matlab DHS figures on vital rates seem to be reliable, the national level DHS estimates may not be as reliable, because women elsewhere in the country may not have reported their children's births and deaths as accurately as did women in the Matlab area