Cassava (Manihot Esculenta) is an important food crop in many tropical countries in Africa, South America and Asia. Limitation of its utilization is due to cyanide acid (HCN). Modification of cassava products should be conducted to increase the value of cassava as food source. Purpose of this research was to determine the effect of bread yeast and tempeh yeast from total titrable acidity and pH from fermented cassava. The analysis includes the measurement of acidity (pH), total acid, and the calculation of total microorganisms by using pH meter, titration method (AOAC, 2000), and counting chumber method, respectively. Growth condition for both fungus were similar, they were able to live on the average pH of 4. Total lactic acid produced by tempeh yeast at 96 hours was 0.878% for a solution and 0.342% for solids. These results were higher than that of bread yeast (0.552% for the solution and 0.259% for solids). However, the growth rate of bread yeast was significantly higher than that of tempeh yeast.