In this paper, an experimental investigation on the fatigue crack growth behavior and the fatigue life of Modified Coach Peel -MCP- specimens are carried out. The MCP specimens with 1 and 1.5 mm thickness and from milled steel are used. The specimens are tested by a 25 kN capacity INSTRON 8802 servo-hydraulic fatigue test machine under the various level loadings with constant amplitudes. During the loading, the crack length and the cycle numbers are measured accurately. The initiation and the propagation of the spot weld specimens are approximately determined by plotting the vertical position of the specimen versus the cycle’s curve. The results show that, the initiation and the propagation of the cracks often occurred for thinner plates. The results also indicate that the crack\\\'s length for thinner specimens is longer than that of the thicker specimens. It is also found that the crack growth gradually in low level loadings while it is usually growth around the nugget and eventually pull out the nugget for high level loadings.

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