In this paper, a new computerised approach to the determination of concentrations of phenolic compounds is considered. In this approach, an integrated artificial neural network (ANN)/laccase biosensor is designed. The data collected (current signals) from amperometric detection of the laccase biosensor were transferred into an ANN trained computer for modelling and prediction of output. Such an integrated ANN/laccase biosensor system is capable of prediction of phenolic compounds concentration of olive oil mill wastewater, based on the created models and patterns, without any previous phenomenological knowledge. The predicted results using the ANN were compared with the amperometric detection of phenolic compounds obtained at a laccase biosensor in olive oil wastewater of 2004–2005 harvest season. The difference between the real and the predicted values was about 5%.