CuInS2 nanowires synthesized by a chemical treatment method were examined using X-ray diffraction and field emission-scanning electron microscopy (FE-SEM). The nanowires, which were identified to have a chalcopyrite structure of CuInS2, were 30–100 nm in diameter and several micrometers in length. A remarkable correlation between the color of a sample with nanowires and their FE-SEM image was disclosed. Photoluminescence spectra of the obtained nanowires were also studied. At low temperatures (∼ 10K) a broad peak centered at photon energy of 2.05 eV was observed. This energy is by 0.5 eV larger than the energy gap of the well-studied crystalline bulk samples of CuInS2. The observed rise in energy can be ascribed to quantum size effects expectedly developing in CuInS2 samples with nanosize dimensions.