Atomic absorption spectrometry is one of the most useful methods applied in trace element analysis, particularly due to high sensitivity and due to relatively low investment and operational costs. This method enables to determine up to 60 elements, metals and metalloids, within a wide concentration range from ug.l-1 to tenth of g.l-1. The contribution deals with fundamental principles of the method and instrumentation, including light sources, optical systems and modern background correction techniques. It systematically describes flame and flameless atomization and sample introduction techniques. Basic analytical parameters of the method, detection power, sensitivity, dynamic working range, standardization approaches, methodology, quality control and assurance are also discussed.