Calvatic acid is a new antibiotic isolated from fermentation of a mushroom, Calvatia craniformis (SHW.) FR. After we had completed this study, we read the recent publication by GASCO et a1.1) on the same compound which is produced by Calvatia lilacina (BERK.) HENN. P. In this report, the production, isolation, physico-chemical properties, structural determination, total synthesis and biological activities of calvatic acid (I) and related synthetic compounds are presented.