Known or potential new fungal starter culture species such as Penicillium camemberti, P. roqueforti, P. nalgiovense, P. caseifulvum, and P. solitum have been cultivated on a cheese agar medium together with the common cheese contaminants P. commune, P. crustosum, P. discolor, P. atramentosum, and P. nordicum. Secondary metabolites were extracted and analyzed by HPLC-DAD and tested for cytotoxicity by using the MTT-cell culture assay. Metabolites such as cyclopiazonic acid, roquefortine C, and penitrem A, previously reported from cheese, were detected together with sclerotigenin, solistatin, meleagrin, oxaline, compactins, diaportins, chaetoglobosins, rugulovasines, verrucolones, anacines, verrucines, cyclopeptines, viridicatins, and viridic acid, all metabolites not previously reported from cheese. The two P. nalgiovense extracts were the most toxic in the MTT-cell culture test. These extracts contained diaportines together with a number of unknown compounds. P. roqueforti extracts were not toxic at all. Fungal extracts from the rest of the studied penicillia were toxic at levels between these two extremes.