Lampteromyces japonicus is the most popular source of mushroom poisoning in Japan. We isolated poisonous substance, illudin S, 40 years ago, which shower strong anti-tumoric activity. Its analogs are now the most hopeful anti-cancer agent. Clitocybe acromelalgia gives unique poisoning which exhibits symptoms similar to acromelalgia and erythromelalgia. We intended to isolate the toxin causing these poisoning but neuroexciatory compounds, acromelic acids A and B, were isolated. They are now known as the most potent glutamate agonists and good reagents for the study of the glutamate receptor of a neurocell.