Fourteen fungal isolates were isolated from soil, ten were found as Aspergillus niger and four Aspergillus terreus. Three enzymes (lipase, amylase and protease) were determined qualitatively and quantitively by chemical methods. Tow isolates from A. niger and A. terreus highly productive was genetically modified by ultraviolet (UV). From each isolate, 50 mutants were randomized obtained and qualitatively tested. Ten of them were quantitatively determined.  Different response was obtained for the three enzymes. After UV irradiation lipase was the most producer, then protease showed higher production in A. terreus only, while production decreased in A. niger, while amylase it showed a slight difference in both isolates compared to the wild. Genetic relationships of the mutants of A. niger and A. terreus were analyzed with a randomly amplified polymorphic DNA–polymerase chain reaction (RAPD–PCR). Results obtained 61.22% genetic similarity (49 total bands) was calculated between parental and mutant strain of A. niger and 48.88% genetic similarity (45 total bands) for A. terrues.