Conjugative transposons were known for many years and were initially discovered for their capacity to disseminate antibiotic resistance genes. They were first named transposons even if they rely on phage-type integrases for their mobility and are now classified as Integrative and Conjugative Elements (ICE). Recently, two families of mobile genetic elements combining DDE transposition and conjugation have been described for the first time in Streptococcus agalactiae (TnGBSs) and in Staphylococcus aureus (ICE6013), respectively. These two families of ICEs are widespread in their respective host species but show a restricted host range. The conjugation imposes constraints on the transposition mechanisms as donor and recipient DNA molecules are in two different cellular compartments. It requires in particular the formation of an independent circular intermediate of transposition. Analysis of Tn GBS transfer revealed that conjugation mechanisms are similar to that of integrase encoding ICEs despite unrelated excision and insertion mechanisms.