This paper presents an approach for prediction of protein functions based on protein-protein interaction networks. For the purpose of prediction, we not only consider the interactions of functionunknown proteins with function-known proteins but also the interactions of function-unknown proteins with function-unknown proteins. Prediction is performed in the context of the entire network. This is a min-cut approach because we try to assign function-unknown proteins to different functional groups in such a way so that the number of intergroup interactions becomes the minimum in the whole network. Also, we show some evaluation results by applying the proposed method to yeast Saccharomyces cerevisiae protein-protein interaction network. However, this is a general method and can be applied to other organisms alike.