Intranasal administration of two doses of potent agonist of luteinizing hormone (LH)-releasing hormone (LHRH), [D-Ser(TBU)6,des-Gly-NH2(10)]LHRH ethylamide (500 micrograms), a 8 A.M. and 5 P.M. on 1 day between day 4 and 9 following the LH peak in six normal women during two consecutive menstrual cycles shortened the luteal phase from 13.6 +/- 0.3 days to 10.9 +/- 0.3 days (mean shortening, 2.7 days; range, 0.5 to 4.5 days) and reduced plasma progesterone levels to 61.3% +/- 9.2% of control. Hormone changes were followed by daily measurements of plasma LH, follicle-stimulating hormone, 17 beta-estradiol, and progesterone during two pretreatment cycles, two treatment cycles, and two post-treatment cycles. No side effect was observed, and apparently normal cycles occurred immediately after treatment. The present data indicate that the intranasal administration of a potent LHRH agonistic analog can induce luteolysis and control time of occurrence of menses in normal women. This finding opens the possibility of a new and physiologic approach to fertility control.