Naringenin was converted to carthamidin and isocarthamidin by Rhodotorula marina yeast. The reaction depended on the age of preculture and time of substrate incubation in reaction mixt. The highest yield of carthamidin was obtained after 24 h of incubation of naringenin added to the 1-day-old preculture, while the highest isocarthamidin concentration was observed after 10 h conversion of naringenin added to the 3-day-old preculture.