evidence: In 1933, Madsen reported on two infants who received immunizations against pertussis shortly after birth and died within 2 hours of their second shot at ages 4 and 11 days, respectively. Although there were other isolated case reports of death following DPT immunization, current concern about pertussis and SIDS dates from March 1979, when the Tennessee Department of Health (Hutcheson, 1979a,b) reported that four sudden and unexplained deaths had occurred since November 1978; these infants had all died within 24 hours following their first DPT immunization. All four children had received vaccine from the same lot (lot A), which was the predominant lot in use in Tennessee at that time. A subsequent investigation confirmed a greater than expected temporal relation between lot A DPT vaccine and SIDS. However, the overall incidence of SIDS in Tennessee did not increase during the time period when lot A was in use, samples of lot A were found acceptable with regard to potency and freedom from toxicity when tested, and no other clusters of cases of SIDS associated with lot A (361,000 doses distributed) were reported (Bernier et al., 1982). Therefore, no other evidence was found to support a causal relationship. [...] The evidence does not indicate a causal relation between DPT vaccine and SIDS. Studies showing a temporal relation between these events are consistent with the expected occurrence of SIDS over the age range in which DPT immunization typically occurs.