Because obesity is thought to play a key role in atherosclerosis through the low-grade chronic inflammation, the present study was designed to investigate associations of body mass index (BMI), body fat, and weight gain with optimized inflammation markers in 1,053 residents who were 40 years of age and older from a rural community (total population = 3,940 in 2000) in Japan. People reporting having a cold and those who did not undergo blood examinations were excluded. C-reactive protein (CRP), fibrinogen, serum albumin, and white blood cell (WBC) count were used as the markers for inflammation, body fat was calculated by a conventional method, and weight change since the age of 20 was assessed. The BMI and body fat significantly increased with CRP quartile, and its correlation coefficients to BMI or body fat were relatively high. Similar associations were found for fibrinogen, serum albumin and WBC. Multivariate-adjusted analysis found a high concentration of CRP was significantly associated with obesity, but attenuated the association in other markers. In an analysis restricted to people aged 40-69 years, body fat levels were more strongly associated with CRP and fibrinogen than with BMI only. Furthermore, only CRP concentrations were significantly elevated according to weight gain. Strong associations of CRP concentration with BMI, body fat, and weight gain were found among elderly Japanese, but not with fibrinogen, serum albumin or WBC.