In this study fatigue behaviour of friction stir welded butt joints of Al-1050-H18 was investigated. Friction stir welds of Al-1050-H18 aluminium alloy material was performed on a semiautomatic milling machine. In the study the same material was welded with different parameters to identify the effect of parameters variation on fatigue behaviour of studied aluminium alloy. FSW tool rotation and transverse speed were accepted as variable parameters while others held fixed. The results of fatigue tests of welded joints showed that the temperature regimes in FSW over required level negatively affect the fatigue endurance limit of the studied joints. Comparison of test results obtained with different tool rotation and transverse speed show that an optimisation is needed to obtain reasonable fatigue endurance limit.