BACKGROUND: We describe here a case of Henoch-Schönlein purpura (HSP) that occurred 10 days after administration of the meningococcal polysaccharide vaccine and came to the attention of a Vaccine Safety Datalink (VSD) investigator (but did not occur in the VSD cohort). Periodic case reports have linked vaccines to HSP. OBJECTIVE: To better understand the potential risk for HSP after immunization with the meningococcal polysaccharide vaccine. PATIENTS AND METHODS: We studied the VSD cohort to estimate the 42-day postvaccination incidence rate of HSP in the VSD population 16 to 20 years of age. Electronic data from all 8 VSD sites were gathered. All subjects aged 16 to 20 years who received a meningococcal polysaccharide vaccine were followed for 42 days after that vaccination for evidence of HSP. Background rates were determined by examining all the nonexposed time of the same cohort. RESULTS: No cases of HSP were seen in the 42 days after 49027 doses of meningococcal polysaccharide vaccine among the entire VSD adolescent and young adult population. The background incidence rate was 4.2 per 100000 person-years. CONCLUSION: These data provide the strongest evidence so far that HSP is not associated with receipt of meningococcal polysaccharide vaccine in the 16- to 20-year age group.