Abstract: A method of rapid resolution liquid chromatography coupled with quadrupole-time-of flight mass spectrometry (RRLC-Q-TOF MS) was established to investigate the distribution of ginsenoside Re (G-Re) in rat various tissues (heart, liver, spleen, lung, kidney and brarin) after a single administration by intravenous injection. The biological samples were prepared by protein precipitation. Chromatographic separations was achieved on a Supelco Ascentis® Express C18 column (50 mm×3.0 mm×2.7 μm) with a mobile phase consisting of solvent A (0.1% formic acid in water) and solvent B (acetonitrile) at a flow rate of 0.3 mL/min. Gradient elution was as follows: 0-15 min, 20%-40%B; 15-20 min, 40%-50%B; 20-22 min, 50%-100%B. Ginsenoside Rc (G-Rc) was used as internal standard (IS). All mass spectrometric experiments were performed on RRLC-Q-TOF MS equipped with an electrospray ionization (ESI) source operated in negative mode. The result shows that the calibration curve is linear in the range of 10-20 000 μg/L for tissue homogenates (r>0.99), the lower limit of detection (LLOD) is 3 μg/L, and the lower limit of quantification (LLOQ) is 10 μg/L. The accuracy, intra-day, inter-day precision and recovery ratio can meet the requirements of the biological samples analysis. As a result, G-Re could be widely distributed in organizations with 20 mg/kg solution by caudal vein injection, which could be detected in different organs and distributed mainly in the lung, spleen, kidney and heart. Lung had a highest affinity to G-Re, which was not easy to pass through the blood-brain barrier and hard to accumulate. This method is simple, sensitive and rapid, which is suitable for analyzing ginsenosides Re in vivo.