This invention provides compounds of the following chemical formula or their pharmaceutically-acceptable salts: ##STR1## wherein R is hydrogen or chloro. Also, the present invention provides a process for the production of the compound of formula I, which comprises cultivating a microorganism having the identifying characteristics of Aspergillus fischeri var. thermomutatis ATCC 18618 or the like, and then isolating the compound of formula I from the fermentation broth. The pyrrolobenzoxazine compounds of formula I of this invention have broad antiparasitic activity, and thus are useful as antiparasitic agents, especially as anthelmintics.