The response of atomic absorption spectrophotometry (AAS) to iron-based wear debris in gas-turbine lubricating oils was measured. It was discovered that the absolute content of wear metal in oil samples was not attainable because of two factors. First, the engine filter system removed substantial amount of debris and secondly, under normal working conditions, the AAS was completely insensitive to iron metal particles and only partially sensitive to iron oxide. Engine health monitoring based on selecting maximum wear debris cutoff values can be misleading if an AAS is used. AAS results however, can be of practical value to show wear metal accumulation trends.