A pentanuclear dysprosium cluster, [Dy(5)(μ(3)-OH)(6)(Acc)(6)(H(2)O)(10)]·Cl(9)·24H(2)O (1), has been synthesized through the reaction of 1-amino-cyclohexanel-carboxylic acid (Acc) and DyCl(3)·5H(2)O. Crystal structural analysis reveals that the metal core of cluster 1 shows an unprecedented trigonal bipyramidal (TBP) geometry. Magnetic studies indicate that the Dy(5) cluster exhibits slow magnetic relaxation.