A number of 2-aralkyltetrahydro-1, 3-oxazines, 3-aralkylamino-1-propanols and 3-aralkyltetrahydro-1, 3-oxazines were prepared and their pharmacological activities tested. Some compounds belonging to the last two groups showed higher bronchodilator activities than aminophilline and even than ephedrine. The structures of tetrahydro-1, 3-oxazines prepared were also discussed.