Batch processes used in the production of various biotechnoloaical (especially microbioloaical) products offer to the control and automation system a Iona line of problems. The purpose of this paper is to express the opinion of the authors in control enaineerino of bioloaical fermentation process, based on total dicrital control of 57 cubic meter industrial fer-menter. The batch reactor control is a classical combination of analog and discrete inputs and outputs, logical connections and start-stop operations. Since most applications involve multiple reactors, it is necessary for the control system to track cycle time of the unit and perform the proper sequencing to match production schedulina and smooth energy demand. The common information base is also needed so that all parts of the system utilize it. The control of each bioloaical livina system is very complicated, so when implementina modern diaital system the users software must be sophisticated, as well as flexible and simple in operation. In order to combine conventional analoc functions, proarammable logic control capability, power and the flexibility of computina technique it is shown that the digital control can practically resolve the wide ranaing demands of batch biotechnoloaical processes. The case study described is one of the first in Europe, in which an industrial batch fermentation reactor is controlled totally by diaital automation system.