The Life Cycle Assessment (LCA) method is widely used to assess the environmental impacts generated during the entire life cycles of products. The traditional process-based LCA (P-LCA), however, has some weaknesses. One of them is incompleteness resulting from the omission of environmental loads on the higher upstream orders of product system. This problem is called “truncation error.” There are some relatively new initiatives to combine the conventional P-LCA with the economic Input Output Analysis (IOA) in one general approach defined as a hybrid LCA. It allows solving different problems, even those which seemed to be unsolvable until now.