Background: Orogranulocytic Migratory Rate (OMR) is defined as the amount of neutrophils move into the oral cavity, through the gingival sulcus. When inflammatory changes occur in the oral cavity, there is an increase in the level of orogranulocytic migratory rate. The oral neutrophil count may be an indicator of the periodontal health status and also it correlates with the severity of periodontal disease. The aim of the study was to assess the relationship of oral neutrophil counts with severity of chronic periodontal diseases and to estimate their levels in response to phase 1 periodontal therapy. Materials and Methods: A total of 66 subjects were selected from the Departments of Periodontics, Annoor Dental College and Hospital, Kerala, India. The subjects were divided into three groups of 22 subjects in each group with two visits. The groups were diagnosed on the basis of gingival index and the number of periodontal pockets. Oral rinse samples of subjects were taken before and 4 weeks after periodontal treatment ((phase 1). Acridine orange was used to stain the cells in the rinse samples. A fluorescence microscope and hemocytometer was used to count neutrophils. Results: There was significant difference in mean value of oral neutrophils before and after treatment for control, moderate periodontitis and severe periodontitis groups. Conclusion: The oral rinse assay was capable to identify a major decrease in oral neutrophil counts in patients who reacted to periodontal treatment (phase 1 therapy). This method is safe, easy, reliable and noninvasive method of quantification of oral neutrophils.