This protocol provides detailed procedures for using flow cytometry to assess key cellular events such as membrane integrity, cell cycle progression, and apoptosis in cells exposed to treatments. Flow cytometry allows for the simultaneous analysis of multiple cell parameters with high sensitivity and precision. The first section covers the assessment of membrane integrity using viability dyes, such as propidium iodide (PI) or 7-aminoactinomycin D (7-AAD), which allow for the differentiation between live and dead cells. The second section describes methods for evaluating the cell cycle by staining DNA with fluorescent dyes, such as DAPI or PI, followed by analysis of cell cycle phases (G0/G1, S, and G2/M). The final section outlines protocols for detecting apoptosis, including Annexin V staining to identify early apoptotic cells and PI staining to detect late apoptotic or necrotic cells. The combination of these analyses can provide a comprehensive understanding of cellular responses to treatments, including cytotoxicity, proliferative status, and programmed cell death.