We have identified RELMγ, a novel member of the resistin-like molecule/found in inflammatory zone (RELM/FIZZ) family in mice and rats. Microarray and real-time RT-PCR experiments revealed a repression of RELMγ mRNA in nasal respiratory epithelium of cigarette smoke-exposed versus untreated rats. The analysis of the physiological tissue-specific expression revealed highest expression in hematopoietic tissues, suggesting a cytokine-like role for RELMγ. RELMγ is most closely related to RELMα/FIZZ1. Despite the high similarity, the expression properties of the two genes are clearly distinct. While RELMγ (approved symbol retnlg) is expressed in rat white adipose tissue, minute to no expression of RELMα was detected in that system. Thus, previous reports analyzing RELMα expression in rat adipose tissue might have been influenced by cross-hybridization with RELMγ. Finally we could demonstrate that white adipose tissue of mice shows strong RELMα expression but only low levels of RELMγ, indicating a species-specific gene regulation.