To investigate the use of yeasts and lactic acid bacteria from natural kefir grain in bread making and its effects on dough and bread quality. The kefir grains were treated with different food-based solutions to enrich the yeast content. Three kefir samples were produced with the treated grains (KAL and SIT) and the control (KEF) kefir grains (untreated). The yeasts isolated from the kefir samples were identified as Saccharomyces cerevisiae and Kluyveromyces marxianus. The microbial and chemical properties were compared with the sourdough sample made with baker's yeast (CON). The amounts of lactic acid and acetic acid varied from 0.51 to 2.99 and 0.20 to 1.0 g/kg, respectively. The concentration of aromatic substances such as ethanol, acetaldehyde, and acetone were determined. The SIT bread achieved the highest sensory score. The kefir grains could be an important natural source in sourdough bread making.