This review examines the use of baker's yeast as a reagent in organic synthesis, with an emphasis on the developments of the last 15 years. The transformations of various classes of compounds are examined, for example, reduction or formation of double bonds, acyloin condensation. The equivalent microbial transformations are compared in relevant cases. 1. Introduction 2. Reduction of β-Keto Esters 3. Reduction of other Keto Acid Derivatives 4. Reduction of α-Hydroxy Aldehydes and Ketones to Vicinal Diols 5. Reduction of Ketones with a Sulfur Containing Functional Group on the α-Carbon 6. Reduction of β-Diketones 7. Reduction of Carbon-Carbon Double Bonds 7.1. Preparation of Bifunctional Chiral Synthetic Building Blocks 7.2. Reduction of Trisubstituted Double Bonds of Larger Synthetic Intermediates 7.3. Reduction of other Trisubstituted Double Bonds 8. Formation of Carbon-Carbon Bonds 8.1. Acyloin Condensation 8.2. Enzymatic Cyclization of Squalenoids 8.3. Carbon-Carbon Bond Formation through Michael-Type Addition 9. Reduction of Carbonyl Groups for the Preparation of Optically Active Fluorinated Compounds 10. Reduction of Heterocyclic Ketones 11. Reduction of Aromatic and Unsaturated Ketones 12. Kinetic Resolution of Cyclic Racemic Ketones 13. Reduction of Nitro Containing Compounds 14. Ester Hydrolysis 15. Water Addition Across the Double Bond of α,β-Unsaturated Aldehydes 16. Dehydrogenation of Unnatural Fatty Acids