The biochemical engineering approach to fermentation has been significant as the engineers have always been engaged in commercial fermentation operations. Perhaps the easiest way to assess and illustrate the role of biochemical engineering in fermentation technology is to first summarise its contributions in various aspects. Biochemical engineering contributions to fermentation technology can be looked at in many different ways. We can go through the characteristic fermentation process flowsheet and look at the main stages: (i) medium preparation and sterilisation, (ii) inoculum preparation, (iii) reaction (fermentation), and (iv) pretreatment for recovery. Alternatively, we can adopt a unit operations approach and collectively examine all activities which have a common basis, heat sterilisation of media, aseptic transfer of fluids, mass transfer (aeration) and so forth.