Biological tissues (in particular those affected by disease) are inherently complex mixtures of different cell types and matrices. This heterogeneity can complicate the interpretation of molecular biological studies performed on whole-tissue extracts if the precise cellular origin of the molecules being tested is not known. Laser-assisted microdissection (LAM) has emerged as a leading histological technique for obtaining samples enriched for specific target cell populations or tissue components for subsequent molecular (especially polymerase chain reaction-based) analysis. This method allows the identification and study of target-specific molecular alterations in heterogeneous specimens, and enables more accurate detection and quantification of target molecules. In this chapter, we focus on tissue microdissection performed with an ultraviolet laser system and describe protocols for the basic procedure and for handling of the samples.