An ever-growing body of scientific evidence indicates that renin–angiotensin system (RAS) blockade can inhibit the evolution of fibrosis in patients with chronic liver diseases, and especially metabolic dysfunction-associated steatotic liver disease (MASLD), although the use of both angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) has not yet been officially identified as a potential fibrosis treatment. This evidence concerns the gene REN and fibrosis.