Microcystins (MCs) are a family of natural toxins produced by cyanobacteria (blue-green algae). Microbial degradation is considered an efficient method for eliminating cyanobacteria and MCs in environmental conditions. This study examines the ability of Trichaptum abietinum 1302BG, a white rot fungus, to degrade microcystin-LR in the harmful algal culture of Microcystis aeruginosa PCC7806. Results showed that microcystin-LR could not be detected by high-performance liquid chromatography after 12 h in algal culture incubated with the fungus. There were also high activities of catalase and peroxidase in algal culture incubated with the fungus. However, similar to the control, they decreased to normal levels after 72 h. Meanwhile, the micronucleus test in the toxicity studies revealed that the degraded algal culture had low toxicity.