Crystal originated defects, referred to as the flow pattern defects, in p-type (100) Czochralski silicon wafers were characterized using nonagitated Secco etching. It was observed that the removal rate of silicon increases with increasing density of the flow pattern defects. From the electrochemical nature of the etching process, the flow pattern defects could act as the electrically active centers which facilitate hydrogen gas bubble evolution and hence the agitation of the etch solution. Annealing at temperatures > 1000-degrees-C was found to cause a reduction in the flow pattern defect density having a uniform depth distribution within the silicon subsurface region. This result implies that the dissolution kinetics of the flow pattern defects could be different from those of oxide precipitates occurring during the formation of the defect-free zone.