This review is intended to give a wide scope on the uses of ion-exchange resins as catalysts or catalyst precursors in organic synthesis, for the preparation of fine or intermediate chemicals. Twelve families of reaction have been covered and presented according to the molecules to be synthesized, regardless of the anionic or cationic nature of the resins; thus, similar to 300 references have been selected from January 1980. In acid-catalyzed reactions, the contribution of both Lewis acidity and Bronsted acidity are mentioned, and, when available, some aspects related to the stability or the recycling of the catalysts are reported. In base-catalyzed reactions, the importance of the thermal stability of anionic resins has been underlined. A table that is included as an appendix provides some data on the resins quoted here.