This article aims at studying and analyzing the status and development of the Shi?ite Muslim minority in Thailand from the 16th century to the present day. The Shi?ite Muslims in Thailand developed and are informally separated into two groups. The original ones call themselves Chao Sen, which means Imam Hussein?s followers, and are descended from Indo-Iranian Shi?ite Muslim ancestors who came from Iran and the Shi?ite States of India during the early 16th century. The others, who are called by the original group Chi A Mai, which means new Shi?ites, converted from other beliefs to Shi?ism under the influence of the Shi?a revival after the Islamic Revolution in Iran in 1979.