Recent papers in Expert Opinion on Drug Safety arrived at different conclusions about the safety of hepatitis B vaccines. In one of these, review of the epidemiological literature failed to confirm the serious allegations raised with respect to vaccination. In the other, review of case reports and the authors' analytical method suggested serious adverse events are associated with the vaccine. In particular, they suggested a strong relationship with multiple sclerosis, the adverse event that has been the focus of several epidemiological investigations and has been found not to be related to vaccination. The method, using data from reported cases, attempted to compute relative and attributable risks using adult Td vaccine as a comparator. The authors made errors in assumptions about the data, including inappropriate use of controls and inappropriate application of epidemiology, rendering the conclusions invalid. Passive reporting data should be analysed with care and used only for hypothesis generation - anything more requires robust epidemiological study.