Intending to explore a new peroral controlled release dosage form using hydroxypropyl cellulose (HPC), an investigation was made on the disintegration and dissolution property of directly compressed tablets of dl-isoproterenol hydrochloride (IPH) held in a simple (PM) or spray dried (SDM) mixtures of HPC and lactose. A commercially available prolonged action preparation of IPH was also examined in comparison with the above preparations. The hardness and disintegration time (dissolution time in the case of SDM tablet) increased with an increase in HPC. SDM was superior in molding property, but the tablet dissolved rapidly compared with PM tablet. A double layer tablet of IPH held in 200 mg of SDM as the initial phase and 300 mg of PM as the depot phase afforded a suitable sustained release property without taking a strikingly rapid dissolution upon changing from No. 1 medium (acidic) to No. 2 (neutral), while the commercially available prolonged action preparation showed a rapid dissolution upon such the change of dissolution media. This sustained release property could be controlled by adjusting the ratio of the active ingredient in the respective layers. Accordingly, this double layer tablet seemed to be applicable to peroral prolonged action dosage forms on the basis of the consideration regarding the absorption, elimination and other properties of the active ingredient.