The growth of Zygosaccharomyces rouxii in soy sauce mash (shoyu moromi) was significantly affected by the pH, temperature, and nitrogen concentration. The effects of pH and temperature on the rate coefficient for growth of Z. rouxii were incorporated in the combined quadratic model form of Davey (Int. J. Food Microbiol., 23 : 295-303, 1994). The model gave a very high degree of goodness of fit between the predicted and observed values. From the results of regression analyses, it was estimated that pH had a 3-fold greater influence on the growth of Z. rouxii at a nitrogen concentration of 1.5% (w/v) than at 1.0% (w/v).