In order to facilitate the study of cell movement, the paper introduces a new automatic picture processing method for tracking and quantifying the dynamics of blood cell motion. The input to the program is a 16 mm cine film of the cell culture viewed in a steady condition. Under the circumstances, the global directional movement tendencies of the group of cells under consideration can be characterized by a Markov chain model. By observing and quantifying the cell paths, it is possible, using this model, to determine the probability that the cell population is moving in a particular direction. This information might be of interest in the study of the effect of substances on cell movement, defects in white blood cell migration, and the general interaction among cells.