Abstract: The present invention is directed to methods and systems for predicting protein secretion into bodily fluids. In an embodiment, a method uses a feature set comprising secretory properties of collected proteins to train a classifier, based on the feature set, to recognize protein features corresponding to proteins that are likely to be secreted into a biological fluid. Another method determines, using a trained classifier and identified features of a received protein sequence, the probability of the protein sequence being secreted into a biological fluid. In an embodiment, a system predicts the secretion of proteins into a biological fluid. The system comprises components configured to construct a protein feature set comprising properties of collected proteins, train a classifier to predict features of a protein that is likely to be secreted into the biological fluid, receive a protein sequence, and identify the received protein sequence as a secretory protein.