Three- and four-color immunophenotyping is routine in traditional flow cytometry, as is measurement of cell proliferation, but there are drawbacks. The techniques cannot analyze cell morphology or permit restaining of cells of interest. This unit describes a slide-based method of immunophenotyping using a laser scanning cytometer. In general, many assays originally developed for flow can be adapted to LSC. Although the speed of analysis is comparatively slow, LSC has the advantage that cells are not lost. Considerable additional information can be obtained by morphological examination and/or by further staining because specimens can be repeatedly analyzed and archived. The method has potential to become a powerful tool in clinical diagnosis.