In order to achieve narrow crystal size distribution (CSD), an important key is the absence of the additional nucleation. It is desirable to observe and investigate the template interface because it is assumed that no additional nucleation occurred at the template interface. The objectives of this present study are observation of crystallization phenomena at the template interface and discussion on the possibility of application of them to produce crystals with a narrow CSD. The glycine-water-c-leucine (template compound) system was used. From the observations of the behavior of crystals on the template interface and our previous studies, it was suggested that there was an exclusive zone between neighboring crystals at the template interface and no additional nucleation occurred. Observation results were analyzed based on the assumption that no additional nucleation occurred between neighboring crystals. The spread of crystals was analyzed by the application of Hubble's law. As the result, it was confirmed that initial crystals were generated at one starting point and spread without additional new crystals forming between crystals on the template interface. From the reasons mentioned above, crystallization phenomena at the template interface can be applied to production of the crystals with a narrow CSD. (C) 2016 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.