Trinuclear chiral (LH)2L2Cu3 (LH = 1,3-diamino-2-propanol, bdapH) assemblies linked by octacyanidometalate(IV) form isostructural one-dimensional (1D) chains consisting of right- and left-handed helixes arranged in an alternate manner: [(bdapH)2(bdap)2Cu(II)3][M(IV)(CN)8]·H2O (M = Mo 1, W 2). Each chain displays helicity with a long pitch around 17.2 Å. The direction of the helix rotation is strictly connected with the conformation of the (LH)2L2Cu3 unit. Right-handed helixes are based on Δ-S,S-(LH)2L2Cu3, whereas left-handed ones contain Λ-R,R-(LH)2L2Cu3 units. Magnetic studies reveal antiferromagnetic interactions through alkoxo-bridges inside trinuclear Cu(II) nodes leading to an ST = 1/2 ground state for both assemblies.