OBJECTIVE:To study absorption characteristics of naringin in situ single-pass intestinal perfusion model of rats. METHODS:UPLC method was established for the content determination of naringin and naringenin in intestinal perfusion samples of rats. The in situ single-pass intestinal perfusion model of rats was adopted to investigate intestinal(duodenum,jejunum,ileum and colon)absorption and metabolic characteristics [apparent permeability coefficient(Peff),absorptivity,metabolic rate] of naringin(10 μ mol/L). RESULTS:The linear range of naringin and naringenin were 1.25-40,1.25-40 μ mol/L(R2=0.999 4, 0.996 6). The detection limit were 0.5,0.4 μ mol/L,and limit of quantitation were all 1.25 μ mol/L. Precision of inter-day and intra-day,recovery and stability in HBSS solution,perfusion fluid of small intestine and colon were all in line with the standard. Peffof naringin in duodenum,jejunum,ileum and colon of rats were(0.28 ± 0.19),(0.71 ± 0.17),(0.30 ± 0.02),(0.59 ± 0.19) (n=6),without statistical significance(P>0.05).Absorptivities were(2.90±2.14)%,(6.38±3.61)%,(3.69±0.56)%,(6.64± 2.12)%(n=6). Naringin could be metabolized to naringenin in 4 intestinal segments of rats,with metabolic rate of(2.98 ± 1.51)%,(2.53 ± 1.31)%,(2.24 ± 1.33)%,(0.70 ± 0.20)%(n=6). The lowest absorptivity and the highest metabolic rate of naringin were occurred in the duodenum,there were statistical significance compared with colon(P<0.05). CONCLUSIONS:Naringin shows poor permeability and poor absorption in the intestinal tract of rats.There was no specific absorption site in the rat' s intestines for naringenin;naringin could be metabolized to naringenin in small intestine and colon,but metabolic rate of naringin in small intestine is higher than in colon.