THE MICROFLORAL pictures of Saint Catherine protectorate, Giza Zoo Garden and Cairo University soil were studied. The obtained 31 microbial isolates were qualitatively and quantitatively screened for laccase production. Aspergillus flavusfrom Saint Catherine protectorate achieved highest laccase production on both solid and liquid media. Identification of this fungal species was further confirmed at the molecular level based on nuclear ribosomal DNA internal transcribed spacer (ITS) identities and was found to be A. flavus strain NG85. The fungus produced statistically highest amounts of laccase after 10 days of growth at 36.7oC and when growth medium was adjusted at pH 5. D-glucose at a concentration of 24 g/l was the best carbon source. The leading nitrogen source was peptone used at 2.51 g/l. Supplementation of copper sulfate at concentration 10 μM to the optimized growth medium caused an increase of 122% in enzyme yield. The crude laccase preparation of A. flavusNG85 from Saint Catherine protectorate showed antiproliferative activity against colon carcinoma cells (HCT-116) and breast carcinoma cells (MCF-7) with IC50 values of 24.3 and 41.3 μg/ml, respectively, and a less inhibitory effect against hepatocellular carcinoma cells (HepG-2).