Palmitoylethanolamide (PEA) is a bioactive fatty acid amide that accumulates during certain types of inflammation. PEA has been identified as a potent analgesic and anti-inflammatory agent, thus representing a promising molecule in the treatment of chronic pain and inflammation. Several studies evidenced the coexistence of multiple mechanisms of action of PEA. For example, PEA may act as an enhancer of the anti-inflammatory and antinociceptive activity exerted by other endogenous compounds (i.e. anandamide), either by increasing their affinity for receptors or inhibiting their metabolic degradation. The ubiquitin-proteasome system is the main extra-lysosomal proteolytic pathways and it is involved in the removal of inflammatory proteins, cell cycle regulators, oxidized and misfolded proteins. The modulation of the proteasome functionality represents an established target in a number of pathologic conditions such as cancer, neurodegenerations and inflammation. In the present study, we investigated the ability of PEA to modulate the enzymatic activity of the proteasome. At first, we studied the effect of different concentrations of PEA on isolated constitutive and immuno-proteasomes. Successively, human cervical carcinoma cells were used as a model to measure PEA effect on tumour cell viability. The effect of PEA on the proteolytic activities of cellular proteasomes has been evaluated and the expression level of several proteasome substrates were determined. Our data propose an additional mechanism of action of PEA, precisely the modulation of proteasome-mediated proteolysis and demonstrate that PEA can affect tumour cells survival through the activation of apoptosis. These findings could represent an important preliminary step in considering PEA as a possible anti-cancer tool.