An active case search for neonatal tetanus (NNT) was conducted in October 2005 in the Kayes region of Mali, in 35 health care facilities that had reported no cases to public health authorities between May and September 2005. Review of records and interviews with health care staff identified four physician-diagnosed clinical cases of NNT. This finding indicates that under-reporting of NNT occurs not only because cases are not seen by trained health care providers, but also because these professionals fail to report diagnosed cases.