The persistent photoconductivity (PPC) of undoped low temperature (LT) grown GaAs has been investigated by temperature-dependent resistance measurements. The PPC phenomenon has been observed under atmospheric pressure in uniformly doped n-GaAs for the first time. It is shown that the recovery temperature is 230 K, and four distinct peaks appear in the PPC spectrum. From the results of secondary ion mass spectroscopy and X-ray multicrystal diffractometry analysis, it is considered that the LT-GaAs layers contain arsenic precipitates or related defects, and that the PPC phenomenon is associated with excess arsenic-related defects in the layers.