This case series describes estimates and estrogen history characteristics of transwomen who received care with the Veterans Affairs (VA) health system and were diagnosed with prostate cancer.  Chart review and data extraction was performed for all cases involving adults with an ICD code for prostate cancer and at least 1 code for transgender identity between January 2000 and November 2022.  Cases were grouped by no prior use of estrogen [ever], former use of estrogen but discontinuation prior to prostate cancer diagnosis, or active use of estrogen at time of diagnosis.  Among 449 people with prostate cancer and transgender identity codes, 155 (35%, corresponding to an estimated 14 cases per year) were confirmed transwomen with prostate cancer.  116 never previously used estrogen, 17 had used estrogen, and 22 actively used estrogen at time of diagnosis.  Median age at diagnosis was 61 and median PSA was 6.8 ng/mL.  All prostate cancers were detected through screening.  98% had not undergone bilateral orchiectomy, and median duration of estrogen use was 32 months among former and active estrogen users.  Overall, 45% were clinical stage T1 and 55% were stage T2.  Compared to people with biopsy grade group 1 or 2, grade group 4 or 5 was found in 23% vs. 71% of patients with no prior estrogen use, 25% vs. 56% in people with former use, and 35% vs. 53% with estrogen use at diagnosis.