Lipases trapped in hydrophobic organic/inorganic matrices result in chemically and thermally stable heterogeneous catalysts that display unusually high catalytic activities. The entrapment of lipases and other biocatalysts by sol-gel encapsulation is an interesting approach to enzyme immobilization, which has the aim of increasing enzyme activity in organic solvents. Investigations that have been carried out to optimize encapsulation and to characterize the lipase-containing gels are reviewed. Possible applications in organic synthesis are indicated.