The present invention relates to a process for the preparation of pyrvinium pamoate, which comprises reacting pyrvinium methyl sulphate salt of formula (II) with disodium pamoate of formula (III), in the presence of a base to processes for the preparation of crystalline Form A and crystalline Form III of pyrvinium pamoate as well as a process for the purification of crystalline Form III. It also relates to crystalline Forms A and III of pyrvinium pamoate and to pharmaceutical compositions containing them.
