The fatigue crack growth behaviour of long and short cracks in two aluminium alloys used in the aircraft industry was characterised in this work. The fatigue crack growth tests on long cracks showed that the alloy Al2524-T351 is more damage tolerant than Al 6013-T6. The threshold values for the propagation of long cracks are approximately 10% higher in Al 2524-T351 compared to Al 6013-T6. The fatigue crack growth tests on specimens with a short corner crack showed for both aluminium alloys that short cracks grow faster compared to long cracks at the same stress intensity factor range and at the same stress ratio. They also grow below the threshold of the stress intensity factor range for the propagation of long cracks. Below the threshold values determined with tests at high, constant Kmax-values short cracks grew but stopped after a prolongation of a few µm. Different models to predict the fatigue crack growth rates in materials were compared and their suitability to describe the short crack growth phenomenon was analysed. The applicability of the stress intensity factor to describe the short crack growth behaviour was also examined. On the basis of the fatigue crack growth data derived from constant Kmax-tests a model was developed with which it is possible to predict the short crack growth behaviour at different stress ratios. The comparison with the experimental short crack growth data showed very good agreement.