Toxicity and bioavailability of arsenic strongly depend on its chemical forms. Chemical speciation analysis of arsenic is getting more and more important to clear exactly the characteristics of arsenic, especially organic arsenicals, in vivo and environment. In this review, the present status of analytical methods for speciation of organic arsenicals is described. Potentiality of liquid chromatography combined with inductively coupled plasma mass spectrometry (LC-ICPMS), especially LC-ICPMS using photooxidation and vaporization techniques for high-sensitive speciation analyses of ultra-trace organic arsenicals, is also described.