A mathematical model has been developed to predict the fatigue life of Shielded Metal Arc Welded (SMAW) cruciform joints failing from toe region. High strength, quenched and tempered steel (ASTM 517 'F' Grade) has been used as the base material throughout the investigation. Design of Experiments (DoE) concept has been used to optimise the required number of experiments. Fatigue experiments have been conducted in a mechanical resonance pulsator, under constant amplitude loading. The model has been developed by Response Surface Method (RSM). Analysis of Variance (ANOVA) technique has been applied to find out the significant factors. By using the developed model, the fatigue life of shielded metal arc welded cruciform joints failing from toe region can be predicted at 95% confidence level. The influences of cruciform joint dimensions on fatigue life have been analysed in detail. (C) 2000 Elsevier Science Ltd. All rights reserved.A mathematical model has been developed to predict the fatigue life of Shielded Metal Arc Welded (SMAW) cruciform joints failing from toe region. High strength, quenched and tempered steel (ASTM 517 `F' Grade) has been used as the base material throughout the investigation. Design of Experiments (DoE) concept has been used to optimize the required number of experiments. Fatigue experiments have been conducted in a mechanical resonance pulsator, under constant amplitude loading. The model has been developed by Response Surface Method (RSM). Analysis of Variance (ANOVA) technique has been applied to find out the significant factors. By using the developed model, the fatigue life of shielded metal arc welded cruciform joints failing from toe region can be predicted at 95% confidence level. The influences of cruciform joint dimensions on fatigue life have been analyzed in detail.