Four new metabolites, italicic acid, dihydro-italicic acid, methyl italicate and italicinic acid, were isolated from culture medium of Penicillium italicum WEHMER. The structures, possessing a 4-ylidene-acyltetronic acid unit, and their biosynthesis were elucidated. Two other new metabolites possessing a chromone skeleton were also isolated and their structures were established as 6, 7-dihydroxy-3-(1'-hydroxy-3'-butanoyl)chromone-5-carboxylic acid and its 1', 2'-dehydrate.