Phytic acid is the principal storage form of phosphorus in many plant tissues and is able to bond with cations that cause mineral deficiency. Application of lactic acid bacteria sourdough for phytic acid reduction in loaf breads is proposed by some researchers, but it seems that there is not much published work on the application of sourdough lactic acid bacteria in flat breads. In this study, effect of several lactic acid bacteria sourdough on flat bread (Sangak) is investigated. Results showed that dough yield (DY), strain type and the percentage of sourdough addition affect pH, phytic acid content and quality of bread. Higher dough yield and higher sourdough addition decreased phytic acid content. Application of Lb. plantarum sourdough with dough yield=300 and 30% addition resulted in 45% decrease of phytic acid content (from 894.66 mg/100g in flour to 507.3 mg/100g in bread). As indicated by panelists, Lb. plantarum sourdough with dough yield=250 and 30% addition can present the greatest effect on overall quality score of the breads.