Studies about pectinases have revealed the biotechnological potential of these enzymes for industrial applications, such as extraction of olive oil, oils recovery of fruit peel, fruit juice clarification, grape and wine production, textile industry, food supplies, textile and cleaning. Pectinases may be classified in esterases (pectin esterase) and depolymerases (polygalacturonases and lyases). These enzymes catalyze the degradation of pectic substances which occur in superior plants, that are constituted by a main chain of polygalacturonic acid branched with other sugars. Pectinases are mainly produced by filamentous fungi, remembering that the fungi Kingdom has over 77000 species many of them not yet studied. The aim of this work was to select among fungi a good producer of pectinases. Fungal isolates were obtained from soil or plants of several Sao Paulo areas, according to Biota program. Cultivation conditions, nutritional sources and physicochemical parameters, were optimized. The assays were carried out with 1% polygalacturonic acid in 100 mM sodium acetate buffer, pH 6.0. The reducing sugar formed was quantified with 3',5' dinitrosalicilic acid (Miller method). Preliminarily, the filamentous fungus Aspergillus niveus was chosen due to the high enzymatic levels of extracellular polygalacturonase activity. Several media were tested (Vogel, SR, Czapeck, M-5, Khouwine and Adams), but the best conditions for production of pectinases were Czapeck medium supplemented with 1% pectin (Sigma) as carbon source, at 30ºC. Time course of pectinase production reveled that the highest polygalacturonase levels occurred after approximately 9 days of growth under standing conditions, or 2 days in a shaker. Among 29 carbon sources tested pectin and citric fruits peels were the best inducers of polygalacturonases. Low levels of pectin lyase and pectate lyase were detected with vegetable residues. Regarding polygalacturonase, it was observed a maximum activity at pH 4.0, optimum temperature at 55ºC and thermal stability up to 90 minutes at 60ºC.