The oxygen precipitation behavior in large diameter (300 mm) Czochralski silicon polished wafers with initial oxygen concentrations between 25-36 parts per million atomic and low carbon content, has been studied following two step heat-treatments (low-high annealing). It was found that an oxygen precipitation retardation and recovery phenomena occurred. Transmission electron microscopy observations showed that extended defect formation is drastically changed from punched-out dislocations in precipitate retardation samples, to stacking faults in precipitation recovery samples. The precipitation retardation phenomenon is consistent with a previous model on smaller diameter wafers; however, the current experimental results for 300 mm wafers indicate platelet precipitate growth during the first low temperature annealing plays a key role in the oxygen precipitation recovery phenomenon.