Putrescine, one of the polyamines, appears to be involved in the production of luteinIsing hormone (LH) surge. In the current study, we have investigated the effects of difluoromethylornithine (DFMO), an irreversible inhibitor of putrescine biosynthesis on the hypothalamo-pituitary-ovarian axis in the female rats. Administration of DFMO subcutaneously reduced hypothalamic LHRH content, pituitary LH content and plasma concentration of LH, oestradiol and progesterone during the pre-ovulatory surge. Time course studies revealed that the drug blunted the LH surge by 50% and the number of ova shed from the oviducts by 68%. This DFMO treatment also caused a significant reduction in the content of putrescine, but not spermidine or spermine in the pituitary at the time of LH surge. These preliminary results indicate that DFMO may probably be a future drug to control ovulation and, in turn, fertility.