This study was conducted to evaluate the influence of Lactobacillus bulgaricus and/or Sterptococcus thermophilus on the fermentation of yoghurt containing 5% (w/v) buckwheat sprouts. The results revealed that after 12 hours of fermentation the appropriate pH, titratable acidity and number of viable cells were attained. At that time, the rutin content of the buckwheat sprout-added yoghurt prepared by the mixed culture method was not changed, but the quercetin content increased greatly. Conversely, the rutin content of yoghurt that only contained Streptococcus thermophilus was decreased while the quercetin content was increased. The total phenol contents as well as the DPPH radical scavenging activities of both the mixed culture and Streptococcus thermophilus yoghurt did not differ significantly. Taken together, the results revealed that the use of a mixed culture of Lactobacillus bulgaricus and Streptococcus thermophilus during the preparation of buchwheat sprout-added yoghurt was desirable due to the decrease in pH and increase in titratable acidity and viable cells that occurred after 12 hr of fermentation. Moreover, phytochemicals in buckwheat sprouts such as rutin, quercetin and phenol compounds were comparatively increased during fermentation and influenced the antioxidant activity in buckwheat sprout-added yoghurt.