Phenethylamine derivatives shown by the general formula <IMAGE> wherein Ro represents a lower alkyl group; R1 represents a lower alkyl group or a lower alkoxy group; R2 represents hydrogen atom or a hydroxyl group; R3 and R4 each represents hydrogen atom or a lower alkyl group; R5 represents hydrogen atom or a lower alkoxy group; X represents oxygen atom or a methylene group; m is an integer of 1-3; and n is an integer of 0-2 and the acid addition salts thereof. These compounds exhibit a strong alpha -adrenergic blocking action and are useful as an antihypertensive agent.
