Fifteen Australian macrofungi were investigated for cytotoxic activity. Ethanol, cold and hot water extracts of each species were screened for cytotoxic activity against normal mouse fibroblast cells (NIH/3T3), healthy human epithelial kidney cells (HEK-293), four cancer cell lines, gastric adenocarcinoma cells (AGS), two mammary gland adenocarcinoma cells (MDA-MB-231, MCF7) and colorectal adenocarcinoma cells (HT-29) with a validated MTT assay. Most extracts derived from Omphalotus nidiformis, Cordyceps cranstounii and Cordyceps gunnii demonstrated significant cytotoxic activity toward a variety of cancer cell lines. In contrast only some extracts from Coprinus comatus, Cordyceps hawkesii, Hypholoma fasciculare, Lepista nuda, Leratiomyces ceres and Ophiocordyceps robertsii displayed significant cytotoxic activity, which was usually selective for only one or two cancer cell lines tested. The least cytotoxic species evaluated in this study were Agaricus bitorquis, Coprinopsis atrametaria, Psathyrella asperospora, Russula clelandii, Tricholoma sp. AU2 and Xerula mundroola.