The technology of laser capture microdissection (LCM) is used to isolate specific regions of tissue samples or specific cells under microscopic observation. Several studies have employed LCM to collect tissue samples or cells from pathological tissues. It can also be used to collect cells from blood smears, particularly when it is difficult to differentiate cells based on expression markers or when the sample volume is limited. This chapter describes a method for preparing peripheral blood or bone marrow smears on glass slides with membranes, followed by staining with May-Grünwald Giemsa solution and cell collection via LCM. In addition, methods for extracting DNA and RNA from the collected cells for the analysis of gene aberrations and expression levels are described.