Laccase has been obtained through two different production systems, the first using Pleurotus ostreatus in solid state fermentation, the second one using Trametes versicolor in submerged culture. Different substrates (by products from yeast, flour and beverage industries) have been evaluated in both systems. Maximum laccase yield with Pleurotus ostreatus (25 U/ml) was obtained in a wheat bran medium. The maximum enzyme concentration level using Trametes versicolor (25 U/ml) was achieved in a submerged system containing 10% vinasse, 4,5% wheat bran and 0,2% molasses per liter of waste. Culture filtrate extracted from Pleurotus ostreatus was used to remove phenol from wastewater. The enzymatic treatment is effective over a wide pH and temperature range. The laccase treatment has been successfully used to dephenolize industrial petrol refinery wastewater. The advantage of laccase dephenolization is that this enzyme uses molecular oxygen as an oxidant.