Garcinia mangostana L. (mangosteen) pericarp containing α-mangostin is predicted to have potential as an anticancer because it can induce apoptosis and has high antioxidant content. Moreover, the preliminary study showed that this extract has high antioxidant activity and cytotoxicity based on the brine shrimp lethality test. This indicates that mangosteen has potential as chemotherapeutic agents or additional therapy in cancers such as colorectal cancer, which the available management is not as effective. To improve its efficacy and bioavailability in the colon as a targeted area, ethyl acetate fraction of mangosteen extract was then formulated into a controlled release encapsulated microparticles by chitosan-alginate material. It is intended that the active ingredient to be released after reaching the colon. In this study, toxicity of mangosteen was investigated because there is still no toxicity data of encapsulated microparticles of the ethyl acetate fraction of mangosteen extract on function of mice's kidneys (BUN/serum creatinine) and liver (SGOT/SGPT). Twenty female BALB/c mice were divided into 4 groups. Three groups were given a single dose of 2, 3, and 5g/kg body weight (BW) mangosteen via intragastric feeding tube and one control group without mangosteen. The findings show that marker of BUN, serum creatinine, SGPT, and SGOT are not significantly different from those of the control in the administration of microparticles ethyl acetate fraction of mangosteen extract at a single dose of 2 and 3g/kgBW, however, significant increases of BUN and SGOT levels were found in single dose of 5g/kgBW. The results indicate that administration encapsulated of microparticles ethyl acetate fraction of G. mangostana L. extract at single dose of 2 and 3g/kgBW cause no toxicity on liver and kidneys function, but the single dose of 5g/kgBW. cause toxicity to the liver and kidneys. Further studies on histopathology examinations of liver and kidneys are necessary to ensure its safety level.