Patients with acute lymphocytic leukemia (ALL), acute myeloid leukemia (AML), some types of non-Hodgkin's lymphoma (nhl) and breast carcinona can be treated with L-asparaginase (L-asnase; EC 188.8.131.52), an enzyme of microbial origin that efficiently reduces the availability of L-asparagine to cancer cells, unable to synthesize the amino acid. The commercial production of L-asnase via bioprocesses involves the Gram-negative bacillus Erwinia chrysanthemi and other Enterobacteriaceae. However, bacterial enzymes can provoke hypersensitivity reactions. Also, their L-glutaminase-like activity can drive to neuronal disorders. These unfavorable characteristics have led to the prospection of new L-asnases in eukaryotic microorganisms and an international effort has been made to seek such enzymes, especially in filamentous fungi from different sources. This presentation reviews the potential of many L-asnase-producing fungi for the obtaining of an effective and low-cost medicament for the above-mentioned cancers.