We report the first observation of oxygen-related deep level defects in solid-source MBE-grown GaInP. Si-doped GaInP samples were studied by deep level transient spectroscopy (DLTS), secondary-ion mass spectrometry (SIMS), capacitance-voltage (C-V) profiles, and photoluminescence (PL). Different amounts of oxygen impurities was introduced into GaInP epilayers by growing with different phosphorus cracking temperatures. Four traps vr ere resolved by DLTS from the GaInP samples. Among them, two traps, with thermal activation energies of 0.45-0.46 and 0.63 0.82 eV, were found to be oxygen-related.