Determination of As species in rice is necessary because inorganic As species (arsenate ($As^V$) and arsenite ($As^{III}$)) are more toxic than organic As (monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)). This study evaluated the As species in Korean and USA rice grains. Levels were determined using microwave extraction and high performance liquid chromatography coupled with inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). Arsenite and DMA were the major species detected in Korean and USA rice. The percentage of inorganic As was 76.94% (54.50-87.86%) for Korean rice and 69.28% (52.94-72.92%) for USA samples. The order and percentage of As species observed in Korean and USA rice were $As^{III}$ (70%)>DMA (24%)> $As^V$ (5%)>MMA (1%), and $As^{III}$ (64%)>DMA (28%)> $As^V$(5%)>MMA (3%), respectively. The $As^{III}$ concentrations were not significantly different in Korean rice grains, compared to USA grains. The high $As^{III}$ predominance indicates an elevated toxic effect of As in rice grains and needs further attention.