Diffuse X-ray scattering from lead chalcogenides (PbS, PbSe, and PbTe) was measured at 15 and 294 K. The increase of the diffuse scattering intensities with the temperature was explained by the thermal correlation effects among thermal displacements of second nearest neighboring Pb-Pb atoms. The contribution from the second nearest neighboring atoms to the diffuse scattering was clearly confirmed.