Background: Recombinant poxviruses have been developed as therapeutic cancer vaccines. Here, we report the safety data from NCI clinical trials with poxviral vaccines. Methods: We evaluated all vaccine injections from 215 patients in 8 clinical trials involving poxviral viral vaccines. The Office of Biotechnology Activities, National Cancer Institute (NCI) Institutional Review Board, and NCI Scientific Review Committee approved all of these trials. Vaccines were consisted of recombinant vaccinia and recombinant fowlpox encoded with 3 human costimulatory molecules (TRICOM), and prostate specific antigen (PSA), or carcinoembryonic antigen, and/or mucin-1. Vaccines were administered at doses between 1.2x10⁸ to 2x10⁹ pfu, subcutaneously, in all patients. Twenty-one patients were also vaccinated intra-tumorally. 84 patients also received other concurrent treatment modalities, such as radiation, celecoxib, ipilimumab, samarium-153, or flutamide on 4 of these trials. All 8 clinical trials involved granulocyte-macrophage colony-stimulating factor (GM-CSF) 100mcg, or recombinant fowlpox encoding GM-CSF at 1x 10⁸pfu as an immune adjuvant. Here, we report here the grade 2 or higher adverse events given at least a possible attribution to vaccine. Results: A total of 1,348 poxviral injections were given in 215 patients. No contact transmission, inadvertent inoculation, or any serious adverse events (AEs) related to vaccinia was observed. Below is the summary of proportion of vaccine administrations associated with specific AEs. Conclusions: These data demonstrate a favorable safety profile of the poxviral vaccines at a broad range of doses, routes of administration, in combination with other treatments, and in various tumor types. Clinical trial information: NCT00060528, NCT00096551, NCT00088413, NCT00081848, NCT00113984, NCT00450619, NCT00450463.