Isocitrate dehydrogenase (IDH) is an essential metabolic enzyme. Over the last two decades, there has been a growing focus on the metabolic derangements that occur with IDH1 and IDH2 mutations. The altered IDH protein leads to accumulation of 2-hydroxyglutarate (2-HG), a metabolite with oncogenic activity via epigenetic mechanisms. The advent of IDH inhibitors has engendered hope in novel and targeted therapies in IDH1/2 mutant myeloid malignancies. We here summarize the basic physiology of IDH, the metabolic and oncogenic consequences of mutant IDH1/2, and the clinical significance of IDH inhibition in hematologic malignancies. We also discuss completed and ongoing clinical trials focusing on the inhibition of IDH proteins, which have demonstrated preliminary indications of efficacy. The promise of IDH inhibition is now being further investigated as a novel therapeutic approach for AML and other myeloid malignancies.