Pyrido-(1,2-a)-1,3,5-triazines which are variously substituted on the triazine ring at the 3-position and on the pyridine ring on any of the available positions are active anthelmintic and antifungal agents and are prepared by condensing a substituted isocyanate or an isothiocyanate with a pyridyl-isocyanate or isothiocyanate. The compounds are disclosed in compositions and methods for the treatment of helminthiasis and fungal diseases.