This paper reports the outcome of a series of tests undertaken on six strand and multi-strand ropes to investigate the effects of degradation and impaired quality on the rope's Bending-over-Sheave (BoS) fatigue endurance. The simulated degradation and quality impairment investigated were: wire breaks (internal and external); plastic wear, abrasive wear, corrosion, slack strands, slack wires and torsional imbalance. Theoretical predictions of rope fatigue endurance have been made to compare with the experimental values, using Feyrer's equation. The investigation indicates that the bending over sheave fatigue endurance of rope is little influenced by degradation and impaired quality, which is primarily dependent on the rope construction and the diameter ratio of sheave to rope. The study establishes methodologies for assessment of the residual BoS fatigue endurance of degraded or impaired rope, which can inform the practical operation, inspection and discard of wire rope thereby enhancing safety.