Neutrophil locomotion was evaluated in three groups of periodontal patients, localized juvenile periodontitis (LJP), post-localized juvenile periodontitis (post-LJP), and generalized juvenile periodontitis (GJP). This was accomplished using regression line analysis, a new method for analysis of neutrophil locomotion in vitro. Neutrophil random migration, chemotaxis and chemokinesis were measured. The present study demonstrates that neutrophil locomotion is reduced in all three patient groups. The reduction in locomotion of the neutrophils in LJP, GJP and in post-LJP patients is due to a decrease of neutrophil migration in the presence of a chemotactic gradient. Furthermore, this decrease in chemotactic response is likely due to a decrease in rate of migration of the population of neutrophils rather than the existence of a large population of poorly responsive neutrophils. Random migration and chemokinesis of these patients' neutrophils are normal. These findings are consistent with our previous findings that the neutrophil locomotor disturbance in juvenile periodontitis is cell-associated and not due to humoral factors, and that there are a reduced number of chemotactic factor receptors present on the cell surface.