Second harmonic generation (SHG) from indium tin oxide (ITO) films on glass substrates has been investigated in detail for the first time. Significant SHG intensity and non-linear optical anisotropy was observed from ITO films due to orientation of the crystal cells. The SHG reached a maximum in intensity at an incident angle of 60 degrees. The effective second order non-linear optical susceptibility chi(eff)(2) was about 2.4 x 10(-10) esu.