Abstract: Hydantoin based compounds useful as inhibitors of matrix metalloproteinases (MMPs), particularly macrophage elastase (MMP-12) are described. Also described are related compositions and methods of using the compounds to inhibit MMP-12 and treat diseases mediated by MMP-12, such as asthma, chronic obstructive pulmonary disease (COPD), emphysema, acute lung injury, idiopathic pulmonary fibrosis (IPF), sarcoidosis, systemic sclerosis, liver fibrosis, nonalcoholic steatohepatitis (NASH), arthritis, cancer, heart disease, inflammatory bowel disease (IBD), acute kidney injury (AKI), chronic kidney disease (CKD), Alport syndrome, and nephritis.