Aims: To evaluate the effect of the combination of carotegrast methyl with rifampicin, a potent inhibitor of organic anion transporter polypeptide, on the pharmacokinetics (PK), safety and tolerability. Methods: In this 2 x 2 crossover study in 20 healthy Japanese adults, 10 subjects received carotegrast methyl 960 mg and rifampicin 600 mg on day 1, and received carotegrast methyl 960 mg on day 8. The subjects in the other sequence received the same treatments but in the opposite order. When the 90% confidence interval (CI) of the geometric mean ratio of the AUC_0-t and C_max for carotegrast, the main active metabolite of carotegrast methyl, with/without rifampicin fell within the range of 0.80 – 1.25, it was deemed that no PK interaction occurred. Adverse events (AEs) were monitored. Results: The C_max and AUC_0-t for carotegrast with/without rifampicin was 11724.5 ± 6097.6 vs 2620.1 ± 1843.0 ng mL^-1, and 55046.0 ± 23427.8 vs 9849.9 ± 4580.6 ng h mL^-1, respectively. The ratios (90% CI) of the C_max and AUC_0-t with/without rifampicin were 4.78 (3.64 – 6.29) and 5.59 (4.60 – 6.79), respectively, indicating carotegrast has a PK interaction with rifampicin. The combination with rifampicin also increased the exposure of carotegrast and its metabolites. The incidence of any AEs with/without rifampicin was five (25.0%) and one (5.0%), respectively. Conclusion: Coadministration of carotegrast methyl with rifampicin significantly increased exposure of carotegrast compared with carotegrast methyl administration alone. However, no increase in the incidence of adverse drug reactions due to coadministration with rifampicin was observed.