Genomic information about Clostridium tetani, the causative agent of the tetanus disease, is scarce. The genome of strain E88, a strain used in vaccine production, was sequenced about 10 years ago. One additional genome (strain 12124569) has recently been released. Here we report three new genomes of C. tetani and describe major differences among all five C. tetani genomes. They all harbor tetanus-toxin-encoding plasmids that contain highly conserved genes for TeNT (tetanus toxin), TetR (transcriptional regulator of TeNT) and ColT (collagenase), but substantially differ in other plasmid regions. The chromosomes share a large core genome that contains about 85% of all genes of a given chromosome. The non-core chromosome comprises mainly prophage-like genomic regions and genes encoding environmental interaction and defense functions (e.g. surface proteins, restriction-modification systems, toxin-antitoxin systems, CRISPR/Cas systems) and other fitness functions (e.g. transport systems, metabolic activities). This new genome information will help to assess the level of genome plasticity of the species C. tetani and provide the basis for detailed comparative studies.