The SPO11 protein catalyzes the formation of meiotic DNA double strand breaks (DSBs) and is homologous to theAsubunit of an archaeal topoisomerase (topo VI). Topo VI are heterotetrameric enzymes comprising two A and two B subunits; however, no topo VIBinvolved inmeiotic recombination had been identified. We characterized a structural homolog of the archaeal topo VIB subunit [meiotic topoisomerase VIB-like (MTOPVIB)], which is essential for meiotic DSB formation. It forms a complexwith the two Arabidopsis thaliana SPO11 orthologs required for meiotic DSB formation (SPO11-1 and SPO11-2) and is absolutely required for the formation of the SPO11-1/SPO11-2 heterodimer. These findings suggest that the catalytic core complex responsible for meiotic DSB formation in eukaryotes adopts a topo VI-like structure.