Semicarbazide-sensitive amine oxidase (SSAO) (EC 1.4.3.6) is widely distributed in nature and catalyzes the oxidative deamination of primary amines. Although SSAO full-length cDNA sequences have been reported for some mammalian species, only a partial 5'-terminal sequence has been confirmed in the rat. In this study we isolated full-length SSAO cDNA from rat aorta and examined its mRNA expression in various rat tissues by real-time PCR, as well as the subcellular and tissue distributions of SSAO activity. The deduced amino acid sequence showed 91% and 80% identity with mouse and human SSAO, respectively. The mRNA was expressed in many rat tissues. Those findings were supported by the broad distribution of SSAO in the body. Thus, a high level of SSAO was shown in adipocytes by both mRNA expression and enzyme activity measurement. The results suggest that SSAO may play an important role in the degradation of biologically active amines in adipocytes.