The connection between gas turbine compressor fouling and expander blade lifetime is studied in a simplified manner for a gas turbine operating in a combined cycle with a constant power output. It is shown how blade materials and compressor fouling rate affect the blade lifetime, and with this background, based on a thermoeconomic approach, the economic aspects of compressor washing intervals and the possibility to find an economic optimum are studied. It is also discussed how it should be possible to employ on-line gas turbine monitoring based on artificial neural networks (ANN) in combination with a database containing blade life behavior in order to improve the blade life management strategy for an optimization of power plant life profitability.