Mass spectrometry (MS) has advanced the diagnosis of Alzheimer's disease. In the present chapter, applications of mass spectrometry for the diagnosis of Alzheimer's disease were summarized. Mass spectrometry showed new exciting results, offered high sensitivity (in the femtomolar range), showed high selectivity, has better accuracy, offered high throughput, were extremely rapid (the entire process required few minutes) and can be used for quantitative, qualitative and imaging. Recent mass spectrometry techniques based on nanotechnologies replaced some of the classical MS techniques. These new technologies improved the diagnosis of Alzheimer's disease. Mass spectrometry covered wide range of Alzheimer's disease biomarkers such as amyloid β, total tau protein (t-tau), α-synuclein, posttranslational modification (phosphorylated tau protein, protein S-nitrosation (SNO), racemization, methylation, chlorination and others) and metals ions. From the analytical point of view, mass spectrometry offered detection of large number of biomarkers in a single test. Mass spectrometry has significantly advanced Alzheimer's diagnosis of living patient and postmortal. Monitoring Alzheimer's biomarkers using MS is very promising for the diagnosis in early stages of the disease. However, the proper interpretation of MS profiling is critical and requires careful investigations. Furthermore, the identification of the biomarkers using MS profile is affected by many key variables that have to be considered during the analysis.