This two-day course provides a concise introduction into the quantitative analysis of peptides and proteins in (complex) biological matrices. As such, the course is useful to researchers working in the fields of both (clinical) biomarker analysis and bioanalysis of therapeutic proteins. As an introductory course, attention is paid to all relevant background aspects, including sample pretreatment, chromatography of peptides and proteins, and mass spectrometry of both proteins and peptides. Relevant workflows in quantitative analysis are outlined and illustrated with application examples.