Abstract The yeasts Saccharomyces and Rhodotorula were grown on spent lucerne whey under continuous culture and other culture conditions; cell yield was 5–6 g/1. The amount of protein and amino acids remaining in the whey after fermentation was determined as a means of checking the ability of these yeasts to scavenge this “amino acid fraction” from the whey. Saccharomyces in continuous culture gave the greater depletion of 2.8 g/1, which was improved by the addition of carbohydrate to 3.7 g/1. These figures were, however, only 50% of the total amino acid fraction in the whey. Of a number of other micro-organisms tested, Pseudomonas sp. and Aspergillus niger showed the most promise, but neither were as convenient as the yeasts.