The 4-N,N-dimelhylamino4-N-methyl slilbazoliurn Losylare (DAST) crystal with large size and nearly square shape was grown in high concentration solution by slope nucleation method coupled slow cooling (SW-SC). Striations considered as planar defects were found on the (001) face along a-axis in the crystal by optical microscope. Some of the striations were continuous while some of them were discontinuous. In addition, the striations were found on (231) diffracting face and such lines did not occur on the (3-21) and (-221) planes. The surface distribution and morphological structure of the crystal were characterized by XRD and atomic force microscope (AFM). The presence of striations in the sample was also confirmed by white-beam synchrotron radiation topography (WBSRT). The mechanism of striations formation was also discussed. (C) 2014 Elsevier B.V. All rights reserved.