The literature data on the application of organosilicon compoundsas water scavengers in reactions of carbonyl compounds is surveyed.The reactions leading to both carbon-carbon (in particular,aldol-type condensations) and carbon-nitrogen bond formation,the synthesis of iminium salts by elimination reactions and heterocyclizationsare considered. 1 Introduction 2 Reactions Leading to Carbon-Carbon Bond Formation 2.1 Aldol-Type Condensations 2.2 Other Reactions 3 Reactions Leading to Carbon-Nitrogen Bond Formation 3.1 Two-Component Condensations 3.2 Three-Component Condensations 4 Formation of Iminium Salts by Elimination Reactions 5 Heterocyclizations 5.1 Synthesis of O- and O,N-Containing Heterocycles 5.2 Synthesis of Pyrimidines by Biginelli Reaction 5.3 Synthesis of Other N-Containing Heterocycles 5.4 Recyclization of 3-Formylchromones 6 Conclusions