There are situations when fatigue precracking of fracture toughness test specimens is not feasible. A case in point is when mixed mode fracture toughness is to be evaluated [1]. It, then, becomes necessary to determine the influence of the notch root radius on the fracture toughness of a material. It is well established that notch root radius has a significant influence on the apparent fracture toughness of a material [2-5]." Usually a critical notch root radius, below which fracture toughness is independent of notch root radius, exists and is measured. We present in this communication the results of an investigation of the effect of notch-root radius on mode I fracture toughness (J~o) of Armco iron and a procedure to correct for the same to arrive at the t rue Jic value.