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Powder metallurgy processing of steels typically results in a material characterized byresidual porosity, whose dimension and morphology, together with the microstructure,strongly affect the fatigue crack growth behaviour of the material. Prismatic specimenswere pressed at 7.0 g/cm3 density from Astaloy CrM powder and sintered in differentconditions, varying the sintering temperature and the cooling rate after sintering. Opticalobservations allowed to evaluate the dimensions and the characteristics of the porosityand the microstructural characteristics for all the investigated conditions. Fatigue testswere performed at R-ratio equal to 0.1 to investigate the threshold zone and to calculatethe Paris law coefficients. All the tests were carried out according with the compliancemethod, and the crack length has been evaluated during the whole test. Moreover KIctests were performed in order to complete the investigation. Both on fatigue and KIcsamples a fractographic analysis was carried out to investigate the crack path and thefracture surface features. The results show that the Paris law crack growth exponent isaround 6.0 for 1120°C sintered and around 4.7 for 1250°C sintered materials. The samedependence to process parameters is not found for the threshold. Values close to 6MPa√m are here found for all variants.