Antagonistic vitamin D receptor (VDR) ligands are considered to be useful for the treatment of conditions involving hypersensitivity to 1α,25-dihydroxyvitamin D3 [1α,25(OH)2D3], such as Paget’s disease of bone, which results in an abnormal bone architecture. To date, several secosteroidal VDR antagonists have been developed. In addition, small molecules and peptides containing the consensus sequence LXXLL [L: leucine (Leu), X: any amino acid residue] have been demonstrated to inhibit VDR-coactivator interactions. Therefore, they are also considered to be drug candidates for reducing VDR-mediated transactivation. In order to bind to the VDR, small molecules/peptides must contain three Leu residues or Leu mimics. Furthermore, small peptides have to have an α-helical structure to efficiently interact with the VDR. It is sometimes difficult to form stable α-helices in short peptides. However, α,α-disubstituted α-amino acids and a covalent cross-linking system have been demonstrated to be useful for stabilizing the helical structures of such peptides. Here, we developed several stabilized helical peptides containing the LXXLL motif and evaluated their ability to inhibit VDR-coactivator interactions. The peptides were prepared by solution-phase methods using EDC and HOBt as coupling reagents. These peptides were examined the inhibitation assay by human VDR on receptor cofactor system, and some of them showed moderate-to-strong activities (~3.2 μM).