The applicability of the modified Diercks equation (MDE) was assessed with elevated temperature low cycle fatigue (ETLCF) data generated by the National Research Institute for Metals (NRIM) for lCr-Mo-V, 1.25Cr-Mo, 2.25Cr-Mo and 9Cr-lMo steels respectively. The modified Diercks equation was assessed with data generated with symmetrical, slow-fast and hold-time waveforms for low alloy steels. The following characteristics were observed: Symmetrical waveforms: Five strain rates were used with these waveforms where predicted life was by a factor of ± x2 for 77%, 87%, 82% and 92% of data points for lCr-Mo-V, 1.25Cr-Mo, 2.25Cr-Mo and 9CrlMo steels respectively. Slow-fast waveforms: Diercks equation was not applicable when the test parameters in tension and compression changed. However, when assessed with such data, predicted life was by a factor of ± x2 for 93%, 66% and 66% of data for lCr-Mo-V, 2.25Cr-Mo and 9Cr-lMo steels respectively. Holdtime waveforms: Tensile only holds of 0.1 and 1 hour were applied where the predicted life was by a factor of ± x2 for 88%, 50% and 100% of test data for lCr-Mo-V, 2.25Cr-Mo and 9Cr-lMo steels respectively.