Abstract The electronic band structure of SbSI crystal was calculated by Mulliken-Wolfsberg-Helmholtz (MWH) method. The semiempirical evaluation of dipole moments for band-to-band transitions was discussed. It was shown the interatomic transitions contribute mainly to the static dielectric constant ϵ 1(0). The interchain interactions should be taken in consideration to describe the dielectric constant. The chemical bonding of SbSI is discussed.