Sophorolipids were produced by single-step batch cultivation of Candida bombicola ATCC 22214 on deproteinized whey concentrate and repeated feed of rapeseed oil. A mild sterilization method for whey was developed. High yields of 280 g dry sophorolipids l(-1) were obtained from deproteinized whey concentrate containing 100 g lactose l(-1) and 300 g rapeseed oil l(-1). Surprisingly, the whey lactose was not consumed by the organism. Growth only on the oil was assumed and a high lipase activity of 24 U per g cell dry weight resulted.