In spite of the fact that vortex formation, in unbaffled agitated vessels, is in most cases an undesirable phenomenon, many Eases exist in chemical engineering where unbaffled systems can be used with greater effectivness than systems with baffles, at the same or even smaller energy consumption levels. Satisfactory results can also be obtained in unbaffled agitated vessels without an air-liquid interface. These facts, viewed in the light of energy problems in the chemical industry, show the current importance of comparative studies of baffled and unbaffled systems. In the present review article some characteristic cases from the fields of fluid dynamics, homogeneous distribution processes, suspension, as well as mass-transfer and heat-transfer operations in baffled and unbaffled agitated vessels are presented and comparatively discussed in relation to their effectivness.