Objective: The fact that metabolic syndrome is accompanied by a low-grade inflammation suggests inflammation may play an important role in the etiology. The aim of our study was to assess the association between heterogeneity of inflammation status and the incidence of metabolic syndrome (MetS) among metabolically healthy obese and nonobese individulas. Methods: This longitudinal study included all metabolically healthy persons who underwent four or more follow-up comprehensive health examinations either annually or biennially from August 2006 through August 2013 at the Health Promotion Center at Samsung Medical Center, Seoul, Republic of Korea. Metabolic health was defined as absence of any component of the MetS. We classified body mass index into categories of normal (18.0-22.9 kg/m2), overweight (23~24.9 kg/m2), and obesity (≥ 25 kg/m2). Hematological parameters such as white blood cells count or its subtypes (neutrophils, lymphocytes, monocytes and inflammatory parameter such as high sensitivity C-reactive protein (hsCRP) were measured. The outcome was the 7-year cumulative incidence of MetS. Results: The person-years follow-up were 17,786 in normal weight, 10,376 in overweight, and 7,391 in obesity group. Baseline age, sex, physical activity, smoking, exercise, fasting plasm glucose, glycated hemoglobin, blood pressure, lipid profile, hematologic parameters, hsCRP were adjusted. Cox regression multivariate analysis resulted in neutrophil count (> 2,750/mm3) was associated with increased incidence of MetS in normal weight (HR, 1.7; CI, 1.29-2.35; p<0.001), overweight (HR.1.59; CI, 1.29-1.95; p < 0.001), and obesity (HR; 1.26; CI 1.10-1.45; p < 0.001). Conclusion: This longitudinal analysis showed the inflammatory marker, especially neutrophil count, is associated with the incidence of MetS in the metabolically heathy obese and nonobese participants. Inflammatory status could be an independent risk factor for the development of metabolic syndrome irrespective of obesity.