The aim of our study was to determine the frequency of Blastocystis hominis in the stool specimens sent to the Parasitological Laboratory of the Mureş County Hospital between October 2003 and May 2004. The 124 inoculated specimens showed positive values in 41.93%. After an incubation in anaerobic conditions at 37 degrees C for 24, 72 and 96 hours in liquid and biphasic media, the last proved to be better (69,24%) at an incubation time of 72 hours.