The mycelial culture of Ganoderma lucidum found in Nigeria was tested on some human pathogenic bacteria using dual and Weller techniques. The mycelial culture was active against all the test organisms: Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa. The bacterium, Escherichia coli showed the highest susceptibility to the mushroom mycelia at 10.6 mm on the first day of incubation which increased to 15.2 mm on the fourth day using the dual method while Pseudomonas aeruginosa showed the least susceptibility of 5.7 mm on the fourth day. In the Weller method the growth of the test organisms were completely antagonized by the mycelia of Ganoderma lucidum as total inhibition was recorded from all the plates. These could be an indication that Ganoderma lucidum can be used in the treatment of diseases caused by these organisms as well as preventive measure against them.