Phenylguanidine derivatives are provided having the structure ##STR1## wherein R is lower alkyl, cycloalkyl, cycloalkylalkyl, lower alkenyl, lower alkynyl, phenyl or benzyl; R.sup.1 and R.sup.2 may be the same or different and are lower alkyl or R.sup.1 and R.sup.2 may be taken together to form an alkylene linking group of 2 or 3 carbons or an o-phenylene group; R.sup.3 and R.sup.4 are the same or different and are lower alkyl, benzyl or phenyl; and n is 0 or 1. These compounds are useful as anthelmintic agents.