Fatigue is a gradual process of local strength reduction. It is a phenomenon of damage accumulation at stress concentrations caused by fluctuating stresses and/or strains. In metals this results in microscopic cracks. These will start to grow under continued cyclic loading until final failure occurs. The process of fatigue is essentially a process of crack growth. In general the damage accumulation, i.e. crack growth, is slow in the early stages and at the end of fatigue life it accelerates very quickly towards failure. All engineering metals are sensitive to fatigue. This dissertation deals with several aspects of fatigue crack growth in aluminum alloy AA 5083 from the threshold regime to final instability.