Abstract: For the production of rhamnolipids which can be used as surfactants, microorganism of the genus Pseudomonas are cultivated in a aqueous medium suitable for the growth of the microorganisms under growth conditions; in this process the microorganisms are cultivated in a continuous submerged culture under aerobic conditions, with a continuous supply of fresh culture medium and with continuous removal of a culture solution and microbial cells (biomass); the culture medium has a composition suitable for limiting growth by means of at least two-fold limitation of essential growth substances; a solution of the rhamnolipids produced as metabolite of the microorganisms is separated from the culture broth. For this purpose a continuously operated bioreactor (11) is suitable.