Novel pyrazolo [1,5-a] [1,3,5] triazines are provided which are active agents to inhibit bronchial constriction with very low chronotropic effects. The novel compounds are prepared by the reaction of an appropiately substituted 1-amidino-5-amino pyrazole with an appropriately substituted trialkyl orthoester. Suitable compositions for utilizing this bronchodilating activity by administration to humans are also disclosed.