Three pressurized water reactor type fuel rods that contained defects representative of those occasionally found in the cladding of commercial reactor fuel rods, that is, a hydrided region, a pinhole-type defect, and an axial crack, were tested under power ramp and power-cooling-mismatch conditions. Operation of the hydrided fuel rod in a power ramp caused a cladding rupture at the location of hydriding and degraded the thermal performance of the rod. Operation of all three defective rods for a short time in film boiling did not seriously aggravate the condition of the rods beyond that experienced by intact rods undergoing the same transient. Embrittlement of the cladding, however, was in excess of that found in intact rods. Although the defective rods withstood the stresses associated with the quenching of the cladding from high temperature film boiling conditions, two of the rods fractured during post-test handling under conditions where intact Zircaloy-clad fuel rods embrittled by oxygen absorption alone would not have fractured. Fuel washout occurred where large, open cladding defects were present. No molten fuel-coolant or molten fuel-cladding interaction was observed.