Nowadays, people have recognized the importance of Monascus fermented products due to their many health benefits. A previous study demonstrated a novel formulation approach for the preparation of nanoparticulate red mold rice (NRMR). The aim of this study is to determine the useability of stable NRMR dispersion by evaluating its safety and mutagenicity with the Ames test. The crude red mold rice (RMR) was processed using a wet milling technology in the presence of distilled water to form an aqueous-based nanoparticle dispersion with a mean particle size of 259.3 nm. The formulated diepersion was found to be homogeneous and exhibited unimodal particle size distribution when analyzed by dynamic laser scattering techniques. Ames test results indicated that the equivalent of up to 1 mg of ethanol extract of RMR per plate exhibited no genotoxicity toward Salmonella typhimurium strains TA 98, TA 100, and TA 102. In the feeding toxicity test, the no observed adverse effect level (NOAEL) of NRMR was found to be 1000 mg/kg/day for both male and female rats. In conclusion, red mold rice can be formulated as a stable nanoparticulate dispersion using wet milling technology. In vitro and in vivo safety evaluations of NRMR indicated that no mutagenic or toxic responses were observed in this study.