Uterine leiomyoma is a fibrotic disease that contains abundant extracellular matrix (ECM) components, particularly collagen fibrils. Aberrant ECM metabolism has been thought to contribute to the pathogenesis of uterine leiomyomas. However, it remains poorly understood whether ovarian sex steroid hormones modulate collagen metabolism in uterine leiomyomas. More recently, a few articles have demonstrated the differential effects of ovarian sex steroids, selective estrogen receptor modulators (SERMs), and selective progesterone receptor modulators (SPRMs) on the induction of the ECM-remodeling enzymes and collagen synthesis in uterine leiomyoma cells. Sex steroids may act to up-regulate collagen synthesis, whereas SERMs and SPRMs down-regulate collagen synthesis. Further study will be needed to clarify the precise mechanism underlying steroidal regulation of collagen synthesis in uterine leiomyomas.