Endometrial cancer1 and oligomenorrhea2 are common risks for women living with androgenic PCOS (WLWP); cyclic progesterone therapy could prevent both. Cyclic oral micronized progesterone therapy (Cyclic OMP; 300 mg at hs/14 days/cycle) also corrects the neuroendocrine origins of PCOS3. Although vaginal progesterone is used in PCOS ovulation induction 4, and short Cyclic OMP decreases LH and/or Testosterone 5,6, no WLWP person-level prospective data with Cyclic OMP therapy are published.A WLWP, aged 31, BMI 20.1, with heavy flow and slightly irregular ~35-day cycles, was unable to tolerate birth control pills. She was prescribed Cyclic OMP (300 mg/h.s. cycle days 14-27)7. She began keeping the Menstrual Cycle Diary© (Diary), a 19-item tool (scored 0-4), during her 1st Cyclic OMP cycle and took no other therapy. This pilot study was designed to understand Cyclic OMP-related experience changes in WLWP: 1) by documenting experience changes on the 1st to the 6th complete Diary; and 2) by assessing follicular phase changes in baseline data (no Rx) vs. cycles 3 and 6. We entered data from six consecutive Diaries into an SPSS (Version 24) database. Analysis #1 used Wilcoxon Signed Ranks Tests (for within-person ordinal data) and #2 repeated measures ANOVA. Research question: What Cyclic OMP-related experience changes occurred for a WLWP? On Cyclic OMP, she spontaneously reported improvements in aching joints, sleep and GI problems. We assessed selected, potentially E2-related Diary changes: flow, fluid retention, breast tenderness, stretchy cervical mucus and anxiety. Cyclic OMP was associated with shorter cycle lengths of 28.17+/-0.8 days. Fluid retention (P=0.000), mucus (P=0.048), and breast tenderness (P=0.000) all decreased, but anxiety and flow were unchanged. Follicular phase only fluid retention significantly decreased (F (1.2, 14.7) = 6.7, P =0.017).Although open-label, these prospective analyses suggest that Cyclic OMP, alone, is related to short-term benefits in androgenic PCOS. Prospective studies and controlled comparative trials of this innovative “luteal phase replacement” PCOS therapy are needed. Reference:1Barry J Hum Reprod Update 2014 20:748. 2Azziz R Nat Rev Dis Primers 2016;2:16057. 3Blank S Hum Reprod Update 2006;12:351. 4Montville C Fertil Steril 2010;94:678. 5Livadas S Fertil Steril 2010;94:242. 6Bagis T J Clin Endocr Met 2002;87:4536. 7Prior J https://hellocluecom/articles/cycle-a-z/the-case-for-a-new-pcos-therapy 2018