A method for the microcrystallization of amobarbital was developed. This method consists of the following procedures : (1) dissolution of amobarbital (J.P. IX) in a hot solvent such as a glycol or glycol derivative, (2) pouring this solution into cold water (3°) while stirring to precipitate microcrystals, and (3) collection and drying of the precipitated microcrystals. The crystalline properties of the pulverized crystals of amobarbital were also studied. The degree of pulverization of amobarbital by recrystallization from glycols and their derivatives decreased with increase in the number of carbon atoms in the hydrophobic chain of these solvents. Examination of pulverized amobarbital was carried out by IR, X-ray diffraction, and DSC-TG, and two kinds of polymorphs were detected.