Extensive remodeling of the extracellular matrix occurs in the ovary during the periovulatory period. Matrix metalloproteinases and their endogenous inhibitors, tissue inhibitors of metalloproteinases, are believed to play integral roles in this highly regulated series of cellular events, but their specific roles remain unclear. Recent cloning studies have identified a novel family of metalloproteinases, the ADAMTS (A Disintegrin And Metalloproteinase with ThromboSpondin motifs) family. The regulated expression of distinct ADAMTS subtypes has been shown to be required for tissue morphogenesis during embryonic development and for maintaining the integrity of tissues in the adult. In the present studies, we have determined that multiple ADAMTS subtypes are present in the bovine ovary using a reverse transcription-polymerase chain reaction strategy. In particular, ADAMTS-1, -2, -3, -4, -5 (also known as ADAMTS-11), -7, -8, and -9, but not ADAMTS-6, -10, or -12, mRNA transcripts were detected in granulosa cells of nonatretic ovarian follicles and corpora lutea. The levels of mRNA for these ovarian ADAMTS were up- or down-regulated or remained unchanged in the granulosa and/or theca cells of the dominant follicle following the preovulatory surge of gonadotropins, depending on the subtype and/or the cell compartment, and in the corpus luteum during the luteal phase of the estrous cycle. The complex expression patterns observed for the distinct ADAMTS subtypes in the granulosa and theca cells of the periovulatory follicle and in the luteal tissues of the bovine ovary suggest that these novel proteases mediate, at least in part, the remodeling events underlying folliculogenesis and ovulation and the formation, maintenance, and regression of the corpus luteum.