Ferroelectric Barium titanate (BaTiO3) thin films have potential applications in optical devices such as frequency doublers. Second harmonic generation (SHG) in MOCVD grown epitaxial thin films of BaTiO3 on MgO substrates is reported at an incident wavelength of 1.064 microns. A number of as-grown films show substantial second harmonic signal. Angular dependence of second harmonic intensity from as-grown films reveals that the orientation of the c-axis in these films are dependent on the growth conditions. We have examined the effect of heating and corona poling on the second harmonic generated by the samples. A higher level of SHG was observed during application of the electric field. On the removal of the poling field the second harmonic signal relaxes back. This behavior may indicate substrate-induced strain stabilization of domains.