Flow cytometry can be used to measure the DNA content of individual cells. The data are usually presented as DNA histograms that can be used to examine the cells' progression through the cell cycle. Under standard growth conditions, fission yeast cells do not complete cytokinesis until after G1 phase; therefore, DNA histograms show one major peak representing cells in G1 (2×1C DNA) and G2 phase (1×2C DNA). By analysis of the duration of the fluorescence signal as well as the intensity of the DNA-related signal, it is possible to discriminate between cells in M/G1, S, and G2 This protocol describes how to prepare cells for flow cytometry and analyze them. We also describe the application of barcoding for more accurate comparison of samples.