Recently, Fukuhara et al. have shown that the novel visfatin is predominantly released from visceral adipocytes and shares metabolic functions with insulin. The authors suggested that there is a relationship between visfatin and the metabolic syndrome in humans. These findings prompted us to clarify the visfatin gene expression from visceral and subcutaneous adipocytes in WOKW rats, as an animal model for polygenically inherited metabolic syndrome, compared to lean Dark Agouti (DA) rats. Moreover, visfatin sequence analysis was performed in WOKW, DA rats, and disease-resistant Fisher 344, Lewis, Brown Norway, and Karlsburg wild rats. The relative gene expression of visfatin displays no significant changes in adipocytes from WOKW rats compared with DA and visfatin sequence analysis of the coding region was identical to the GenBank. But, we found length differences of two repeats, GT and GA, in intron 2 between the strains. In summary, the relative visfatin gene expression is not associated with the metabolic syndrome in WOKW rats. (c) 2005 Elsevier Inc. All rights reserved.