Oligosaccharides are carbohydrates with a low molecular weight, which, when nondigestible, can produce bifidogenic activity and several other effects to human health. Oligosaccharides can be found naturally in foods or are produced by the synthesis from disaccharide substrates or by the hydrolysis of polysaccharides. Although it has yet to be improved, the hydrolysis of polysaccharides is the best choice for oligosaccharide production on a large scale, due to its reproducibility and smaller cost. This review concisely presents the main processes for the production of oligosaccharides by depolymerisation of polysaccharides (enzymatic, acid, and physical hydrolysis), taking into account their advantages, disadvantages, and perspectives.