A probabilistic method of determining the remaining life of reformer furnace catalyst tubes is presented. Method of analysis, required data input, and model outputs are described. The methodology employed will allow calculation of the cumulative probability of failure, time-to-crack initiation, and time-to-failure in terms of furnace operating hours. On the basis of program results, recommendations can be provided for the optimum time of tube replacement and non-destructive examination. Tube replacement strategy can be determined on a row-by-row basis. This model is highly effective when used to manage operating conditions for the life optimization of new tubes. Keywords: probabilistic remaining life assessment, creep-fatigue interaction, centrifugal cast tubing, heat-resistant stainless steel, high-temperature application, statistical analysis, Monte Carlo simulation, probability of failure.