Vietnamese soy sauce has been made for centuries using traditional methods, in villages in Northern Vietnam. This sauce differs from other Asian products not only in its raw materials but also in its flavour characteristics. Presently small scale Vietnamese soy sauce is produced mostly with a standardised inoculum of Aspergillus oryzae under natural conditions. This usually gives rise to a product of variable and inconsistent quality. The aim of this study was to standardise the fermentation condition for the production of Vietnamese soy sauce, so as to obtain a product of more consistently good quality. Aspergillus flavus var columnaris was used as the inoculum. The inoculum was prepared by growing the organism on sticky rice at 20 and 37 degrees centigrade under aerobic conditions. At 20C, a high protease activity was recorded in the inoculum while at 37C, a high amylase activity was observed. The two different inocula prepared at 20C and 37C were then used in the preparation of soy sauce in the normal manner. The inocula were mixed with cooked roasted soy beans and salt water, left to age for 1 month at 30C, followed by ageing at 20C for 2 months. The products obtained were subjected to sensory evaluation and analysed for glucose, fructose, amino acids, nitrogen, ethanol and NaCI. Both inocula produced products of acceptable quality. The inoculum produced at 20C had a higher sensory evaluation score. It also contained a higher level of protein (14.5% compared to 11%), and a higher sensory evaluation score (6.9 compared to 3.2) when compared to a commercial Vietnamese sauce, Hanoi soy sauce. This valuable information will now enable small scale producers to produce this product throughout the year by controlling the temperature, and not be limited to the summer season, as has been the case with the traditional method of production. / Master of Science (Hons)