In the present study the influence of the carbon black quality parameter "fines content" was investigated with respect to the degree of long chain branching of EPDM polymers, the mixing process and the compound properties. It was found that the fines content in combination with the degree of branching influences the mixing process and some compound properties significantly. The power consumption of the mixer varied as a function of the fines content and the Black Incorporation Time was extended at increasing fines content. As a consequence, the carbon black and sulphur dispersion of the compounds showed variations, too. The effects are most pronounced if polymers of high degree of long chain branching are applied. Furthermore, it was found that the presence of processing aids added to the polymer bale lead to completely different process behaviour. In that case the influence of increasing fines content helps to attain good carbon black and the sulphur dispersion, even if polymers of high branching levels are regarded.