The effect of naphthaleneacetic acid (NAA), benzylaminopurine (BAP), L-glutamine (L-gln), and combinations of these substances on mycelial growth of Phaeolus schweinitzii was studied in vitro. NAA (1 mg x l-1), L-gln (500 mg x l-1) and a combination of NAA with L-gln inhibited the growth of fungal mycelium. BAP (1 mg x l-1) enhanced the inhibitory effect of NAA while in combination with L-gln it reduced the inhibitory effect of L-gln.