This paper presents a rapid flow cytometric method for determining the DNA content per cell using propidium iodide staining. The authors compare this method with traditional techniques such as acriflavine staining and mithramycin staining, highlighting the advantages of propidium iodide staining, including its speed (5 minutes), minimal sample requirements (1-2 drops of blood or 1-2 million cells), and the avoidance of cell clumping. The study uses human leukemic lymphoblasts (CCRF-CEM cell line) and bone marrow samples to demonstrate that direct staining with propidium iodide yields DNA distribution histograms that are identical to those obtained after fixation and RNase digestion. The method is particularly useful for clinical studies where small biopsy samples are available and time is a critical factor. The authors conclude that propidium iodide staining is a convenient and accurate alternative to traditional staining methods, offering significant advantages in terms of sample size, processing time, and reliability.This paper presents a rapid flow cytometric method for determining the DNA content per cell using propidium iodide staining. The authors compare this method with traditional techniques such as acriflavine staining and mithramycin staining, highlighting the advantages of propidium iodide staining, including its speed (5 minutes), minimal sample requirements (1-2 drops of blood or 1-2 million cells), and the avoidance of cell clumping. The study uses human leukemic lymphoblasts (CCRF-CEM cell line) and bone marrow samples to demonstrate that direct staining with propidium iodide yields DNA distribution histograms that are identical to those obtained after fixation and RNase digestion. The method is particularly useful for clinical studies where small biopsy samples are available and time is a critical factor. The authors conclude that propidium iodide staining is a convenient and accurate alternative to traditional staining methods, offering significant advantages in terms of sample size, processing time, and reliability.