The invention relates to crystalline forms of (3S,4S)-1-Cyclopropylmethyl-4-{[5-(2,4-difluoro-phenyl)-isoxazole-3-carbonyl]-amino}-piperidine-3-carboxylic acid (1-pyrimidin-2-yl-cyclopropyl)-amide; processes for the preparation thereof, pharmaceutical compositions containing such crystalline forms, pharmaceutical compositions prepared from such crystalline forms, and their use as a medicament, especially as CXCR7 receptor modulators.本發明係關於(3S,4S)-1-環丙基甲基-4-{[5-(2,4-二氟-苯基)-異㗁唑-3-羰基]-胺基}-哌啶-3-羧酸(1-嘧啶-2-基-環丙基)-醯胺之結晶型;其製備方法,含有該等結晶型之醫藥組合物,由該等結晶型製備之醫藥組合物及其作為藥品、尤其作為CXCR7受體調節劑之用途。