Progesterone hypersensitivity is a rare phenomenon which can occur after both endogenous and exogenous exposures. We present a case of hypersensitivity to various forms and routes of exogenous progesterone. A 27-year-old female presented with primary infertility. Investigations revealed Grade 1 endometriosis and polycystic ovary syndrome. Three cycles of intrauterine insemination were attempted which were unsuccessful and in vitro fertilization was proceeded. Six blastocysts of Grade A were formed and cryopreserved. Artificial cycle was used for endometrial preparation for frozen embryo transfer (FET). However, due to failure to use exogenous progesterone due to hypersensitivity reaction, Modified Natural Cycle (MNC) was used. A follicle was formed using ovulation induction with tamoxifen and human menopausal gonadotropin. Ovulation was induced by human chorionic gonadotropin (hCG), and natural progesterone from corpus luteum was used. FET was done when endometrium was 8 mm. Pregnancy was confirmed by transvaginal ultrasound and β-hCG levels and continued uneventfully. Endogenous progesterone can be used as an alternative for endometrial preparation for FET in patients with exogenous progesterone hypersensitivity.