British Columbia (B.C.) provides an excellent opportunity to study the accuracy of assigning Underlying Cause of Death (UCOD) in Down syndrome. The study was designed to evaluate the effect of inappropriate interpretation of guidelines for completing the death certificate. All B.C. livebirths identified as having Down syndrome during the period 1952-1981 were collected from the records of the B.C. Health Surveillance Registry. Of the 1,337 affected individuals identified, 324 (24.2%) had died. The death certificates on these individuals were reviewed to assess from the information on the death certificate whether the underlying cause of death appeared to have been assigned in accordance to World Health Organization coding guidelines. The UCOD appeared to be assigned appropriately for 165/315 cases (52.4%). It is possible that in the situation where an easily recognizable condition such as Down syndrome is present, the need to identify the actual UCOD may be viewed as less urgent compared with cases where an apparently "normal" individual dies.