Changes in naphthalene (Naph), phenanthrene (Phe), pyrene (Pyr), benzo(a)pyrene (BaP) and benzo(ghi)perylene (BgP) concentrations in a mixture of sewage sludge and the organic fraction of municipal waste were determined during composting and anaerobic digestion. The processes were carried out on a laboratory scale. The selected polycyclic aromatic hydrocarbons (PAHs) were analyzed in the samples using gas chromatography-mass spectrometry. The rates at which the PAHs concentrations decreased were evaluated during composting and anaerobic digestion. The selected PAHs degradation kinetics were compared during these processes. The most important conclusion of this work is that composting is much more effective than anaerobic digestion in removing five PAHs from a mixture of sewage sludge and the organic fraction of municipal waste.