The Indian laburnum (Cassia fistula L.), known as “Amaltash” in Hindi, has great medicinal importance. It has yellow colored, very attractive, beautiful flowering panicles, which makes it an important ornamental avenue tree. However, its habitat can be lost due to the physical quality of its pollen being affected by various types of pollutants, resulting in heavy flower and fruit drop. Pollen cryopreservation is a complementary germplasm conservation strategy for many plant species. This approach can be used as an alternative strategy to conserve the nuclear genetic diversity (NGD) of Cassia fistula L. In addition, cryopreserved pollen can be used to overcome geographical, seasonal, and physiological barriers in future breeding programs. This chapter describes the method of cryopreservation of pollen grains of C. fistula and collection and subsequent cryopreservation in liquid nitrogen. The efficiency of this protocol has been demonstrated by the high percentage of pollen viability after cryopreservation. The establishment of a “Pollen Cryobank” for species, in addition to fulfilling various other needs, considerably reduces the maintenance of crops in the field for the regular supply of pollen.