Abstract With respect to the importance of energy consumption reduction in industrial plants, an attempt has been made to specify the most important parameters affecting energy consumption of plastic injection molding process as one of the most energy intensive processes in plastics industry. In this regard, the specific energy consumption of six hydraulic injection molding machines and the profile of their energy consumption over one cycle of injection molding process were measured to assess the effect of different machine related and process related parameters on energy consumption and realize energy saving opportunities in the injection molding process. Results showed that among all quantitative parameters, throughput and total cycle time, which are process related parameters, have the most important impact on the specific energy consumption of the process. Whereas, the most important effect of machine related parameters were found to be on the peak power of energy consumption, which gives an insight to industrial plants how to reduce the maximum electrical demand of the plant. In addition, it was proved that each hydraulic injection molding machine has a unique profile of energy consumption depending on the design of the machine and process, and then according to these profiles, three types of process designs were identified.