Lamellar CuInS2 material grown in a steep temperature gradient shows heterogeneous composition and complex photoeffects. Besides predominant n-type behavior, the electrode surface has areas with intrinsic or p-type conductivity, the latter usually corresponding to indium-rich regions. An inverted (cathodic) photocurrent is observed at n-type electrodes polarized under accumulation conditions. Both spectral dependence, with a pronounced peak for energies around the bandgap, and quantum yields >1 suggest that these photoeffects originate from photoconductivity phenomena in the crystal bulk. Variability in electronic properties limits the average performance of the material in solar cells.