Human tauopathies including Alzheimer's disease are characterized by alterations in the post-translational modification (PTM) pattern of Tau, leading to the formation of insoluble aggregates, neuronal dysfunction and degeneration. We immunoprecipitated Tau from post-mortem brain tissue of early stage Alzheimer's disease patients and age-matched controls, and analyzed PTMs on this soluble pool of Tau protein. In addition to known serine, threonine and tyrosine phosphorylation events, we identified a number of previously unknown monomethylation events on lysines in both control and Alzheimer's patient tissues.