The time dependence of the photorefractive effect in single mode LiNbO3 directional couplers at low powers of 3.2 μ.W in the GaAs wavelength spectrum is discussed. The transient response was found to De consistent with bimolecular relaxation processes which caused tae saturation of this effect to occur for times on the order of an hour. Additional effects having much longer decay times were observed consistent with those found in bulk LiNbO3.