► Acyclic diaminocarbenes (ADCs). ► ADC-based catalysts for organic transformations. Starting from the first reported application of complexes bearing acyclic diaminocarbene (ADC) ligands as catalysts ca. 5 years ago, these compounds have been successfully employed for several useful organic transformations, viz. cross-coupling reactions (Suzuki–Miyaura, Heck, Sonogashira, Buchwald–Hartwig, and Kumada) and some cyclizations/additions to substrates having the CC and CC bonds. In these processes, ADC–metal complexes behave as an attractive alternative to extremely popular N-heterocyclic carbenes (NHCs). This review attempts to systematize studies published until now and to explain various observations and initial ideas on mechanisms and driving forces of ADC-based catalysts as well as to draw attention to the potential and the advantages that application of ADCs gives to synthetic organometallic and organic chemistry.