Sodium theophylline monohydrate was precipitated from ethylene diamine solution of theophylline by adding aqueous sodium chloride solution to the system with or without ethanol. The dried precipitates were redispersed in the filtrate without ethanol and were agglomerated with water liberated from the system by adding chloroform and ethanol to the filtrate with agitation. The sedimentation velocity of the agglomerated precipitates and their sedimentation volume at equilibrium were investigated to identify a suitable composition of the medium for agglomeration by gradually increasing the chloroform fraction in the medium. The sedimentation volume slightly increased before dropping drastically at 41% chloroform fraction, at which the precipitates were microagglomerated after passing through a flock stage of high bulk volume. At 56% chloroform fraction, the sedimentation volume sharply decreased again because of secondary agglomeration of the microagglomerates. The sedimentation velocity of the agglomerated precipitates increased with increasing chloroform fraction of the medium in the range above 41%. The agglomerate size increased drastically when the secondary agglomeration occurred. No changes in the sizes and shapes of the elemental crystals were found even after agglomeration. A triangular phase diagram was obtained to described a suitable composition of the medium for agglomeration. It was also proved that simultaneous agglomeration with crystallization was possible in a mixture of four liquids, i.e. ethylenediamine solution of theophylline, aqueous solution of sodium chloride, ethanol and chloroform, with a suitable composition.