Several antiaromatic metallacycles have been reported in the past 5 years, opening an emerging area of (anti)aromaticity and organometallic chemistry. In this work, we briefly review the synthesis and characterization of these complexes. Generally, experimental criteria, including planarity, bond length alternation, NMR chemical shift, chemical transformation, and theoretical criteria, mainly involving NICS, AICD, ASE or ISE, are applied for the antiaromaticity judgement.