The lack of effective diagnosis of testicular disorders leading to infertility is a major problem in reproductive biomedicine. A better understanding of male infertility related to abnormal spermatogenesis associated with differential gene expression is of interest. We are working on a novel hyaluronan binding protein (HABP1) that interacts specifically with HA and facilitates HA mediated processes including sperm-oocyte interaction1 and sperm motility2. Sequence analysis of HABP1 from human fibroblasts reveal its identity with SF2/p32, the protein copurified with alternate splicing factor3 and globular head of C1Q thus represented in human Chromosome 17p13.34 as synonym HABP1/p32/C1QBP. HABP1 is synthesized as a proprotein which forms mature protein by cleavage of initial 73 amino acids. This proprotein form is extremely labile and detected only in pachytene spermatocytes and round spermatids in germ cells in adult testis5. Further analysis demonstrates that though mature form of HABP1 is present in the testis, its precursor form was not found in testis of 7, 14, 21 and 28 day old rat, but is present only in pachytene spermatocytes and round spermatids of testis of 21 day and 28 day old rats. With spermatogenic arrest, HABP1 is lost from pachytene and round spermatids suggesting that the expression of HABP1 proprotein may be crucial for spermatogenesis6. Earlier we reported on the reduction in the level of HABP1 on sperm surface in asthenozoospermic and oligospermic patient7. In continuation, we have also demonstrated the interaction of HABP1 with zona pellucida of buffalo and shown that the supplementation of IVF medium with rHABP1 can promote the capacity of sperm binding to oocytes under invitro fertilization conditions even in presence of D-mannosylated albumin (DMA), known to inhibit sperm oocyte interaction8. Thus we propose to use HABP1: 1. as a diagnostic marker for male infertility and spermatogenic arrest in testicular biopsy. 2. in IVF medium to promote sperm oocyte interaction.