Additional efforts will be needed by European countries to improve the energy efficiency, as with current trends the 20% objective will be missed. Small and medium-sized enterprises (SMEs) manufacturing sector is a promising field, as SMEs are less energy-efficient than larger enterprises. Several studies investigated the barriers to the diffusion of technologies and practices for industrial energy efficiency, but little attention has been paid to understand the factors affecting the perception of such barriers by SMEs. In this multiple case-study, we have investigated 20 Primary Metal manufacturing SMEs in Northern Italy. Economic and information barriers are perceived as the major issues. Interestingly, firm's size, innovativeness of the market in which enterprises operate, as well as product and process innovation are factors affecting barriers to energy efficiency. Differences have been observed within SMEs, especially for information and competence-related barriers. In particular, a more innovative external context in which enterprises operate and a greater production process complexity seem to reduce barriers. Moreover, more product innovative enterprises seem to have a lower perception of behavioral and technology-related barriers. The results of this exploratory investigation provide useful suggestions for policy design and further research on industrial energy efficiency.