The novel macrocyclic decanuclear manganese(III) 30-metallacrown-10 compound [Mn10(RS-3-chmshz)10(DMF)10]·9DMF (1) was synthesized by self-assembly and characterized (H3RS-3-chmshz = N-((R,S)-3-cyclohexenoyl)-5-methylsalicylhydrazide). Compound 1 is a 30-membered decanuclear metallamacrocycle and crystallizes in triclinic space group P21/c, in an alternating …ΔΛΔΛ…-type chiral configuration. The decanuclear systems measure ~2.6 nm in diameter and ~1.1 nm in thickness. The racemic N-(R,S)-3-cyclohexenoyl group directing into the cavity of the metallamacrocycle shows the alternate R,S chiral configuration. Magnetic measurements on the title 30-metallacrown-10 compound show weak antiferromagnetic exchange interaction.