Thiamine requirement of binucleate Rhizocronia AG-A ~ AG-S was determined by using liquid and solid media. Only AG-H was thiamine auxotrophic, others were thiamine autotrophic. Although AG-A. Ba, Bb, I, and K were thiamine autotrophic. but their growth was enhanced by thiamine. To determine thiamine requirement of binucleate Rhizoctonia with so lid medium by using agarose to replace agar, the results were smilar to those in liquid medium. It is suggested that solid medium with agarose as a solified substrate is a simple, rapid method to investigate thiamine requirement of the fungi.