Twenty-two yellow tree monitors (Varanus bengalensis) were trapped and transported from 5 provinces, namely Lampang, Phitsanulok, Kamphaeng Phet, Tak and Prachin Buri to look for the infective larvae stage of Angiostrongylus cantonensis. In 4 provinces all of the yellow tree monitors were infected with the infective stage larvae of A. cantonensis altogether. Twenty-one of the 22 yellow tree monitors (95.5%) in the five provinces were infected. Our results of this study extend our knowledge of natural prevalence of A. cantonensis in yellow tree monitors. The snail eating habit of the yellow tree monitor might possibly be the source of the larvae.