Disposable bioreactors have gained an increasing importance in recent years in the pharmaceutical production. Wave-mixed reactors were among the first systems which were applied. In contrast to stirred tank reactors, wave-mixed bioreactors are characterized by low shear forces while the gas exchange is realized by the large gas-liquid interface. Oxygen transfer rates obtained are often in a range between 50 and 300 h–1. By applying nutrient-limiting fed-batch cultivations, in which the oxygen consumption of a culture is controlled, bacteria can be also cultivated in wave-mixed reactors. This article describes the successful scale-up of an Escherichia coli fed-batch cultivation from the 12-L to the 120-L scale using a disposable bioreactor, in which a final biomass concentration of 45 g L–1 was obtained.