The invention relates to a new crystalline form of the acetate salt of, 3-(1.H.-indol-3-yl)-4-[2-(4-methyl-piperazin-l-yl)- quinazolin-4-yl]-pyrrole-2,5-dione, which may be used for example for transplantation.本發明係關於一種3-(1.H.-吲哚-3-基)-4-[2-(4-甲基-哌嗪-1-基)-喹唑啉-4-基]-吡咯-2,5-二酮乙酸鹽之新穎晶體形式,其可用於例如移植。