A fractured HPTR blade belonging to an aeroengine, which failed in service was sent to the laboratory for analysis. Examination revealed that the blade had failed by fatigue. Fatigue crack was found to have initiated on the leading edge at about 70 mm height from the blade root platform and propagated progressively over about 50% of the blade cross section before giving way to final overload failure. Although micro-fractographic features were largely obliterated due to heat effects, gross fracture features indicated that the fatigue crack had originated on the convex surface, close to the leading edge. At the crack origin region, the blade-wall thickness was found to be very minimal (-200 um). This low wall thickness had resulted due to improper liquid metal flow in the mould during blade casting process. Hence, the primary reason for the fatigue failure of the HPTR blade can be attributed to casting defect.