It is well known that grapefruit juice (GFJ) possesses components that can modulate drug pharmacokinetics. For instance, furanocoumarins (e.g., bergamottin) found in GFJ could inhibit cytochrome P450 3A4 thereby affecting first-pass metabolism of xenobiotics. In addition, flavonoids in GFJ have been demonstrated to inhibit organic anion-transporting polypeptides (OATPs). The effects, however, were thought to occur locally in the intestinal lumen. Recently, therapeutics targeting the liver via hepatic-specific OATPs have shown promise at increasing efficacy while reducing off-target effects. Therefore, the objective of our current work was to elucidate the potential systemic effect of GFJ on liver OATPs using cellular in vitro models. First, two commercially available ruby red GFJ brands were used at a single dilution and co-incubated with probe compounds in human embryonic kidney (HEK 293) cells stably transfected with major hepatic uptake transporters including OATP1B1, OATP1B3, or OATP2B1. The data indicated that GFJ, even at a dilution of 1% (v/v), was able to significantly reduce the active uptake of pravastatin or rosuvastatin in the HEK-OATP cells. The extent of inhibition was compatible between the two GFJ brands. Diluted GFJ did not have any effect on compounds that are passively taken up into cells indicating that OATP inhibition was the primary cause for the observed outcome. Furthermore, active uptake of probes significantly decreased as the concentration of GFJ increased. At 10% GFJ, pravastatin uptake fell by 80% compared to controls in HEK-OATP1B1 and HEK-OATP1B3 cells, whereas the same level of GFJ was attributed to a 50% decline in rosuvastatin uptake in HEK-OATP2B1. Additionally, sandwich-cultured human hepatocytes (SCHH) were utilized to ascertain the extent of GFJ modulation on a more physiologically representative model. As pravastatin does not undergo extensive metabolism, its application in the SCHH model permitted assessment of GFJ inhibition on OATP-mediated uptake. At 5% GFJ concentration, pravastatin uptake in SCHH was reduced by 67 to 100% compared to controls for the two GFJ brands. In summary, the results indicate that GFJ, even at low concentrations, has the potential to significantly modulate hepatic OATP function in two separate in vitro models. Moreover, the uptakes of OATP substrates were inhibited by GFJ in a dose-dependent manner. Further work is ongoing to explore the degree of GFJ inhibition of OATP uptake in vivo.