Uterine leiomyoma has become a significant health concern affecting one in forth women in reproductive age in Taiwan, according to the Ministry of Health and Welfare. The associated symptoms can lead to reduced life quality and women ultimately seeking for surgical intervention. Adlay extract possesses anti-tumor activity and has shown to inhibit sarcoma cell proliferation and tumor progression. In present study, viability of ELT3 cells was tested to screen for different fractions of adlay extracts, as well as various phenolic compounds and flavonoids. The active adlay fractions and compounds were then tested on primary human leiomyoma cells. Cell cycle profiles of ELT3 cells were analyzed in order to determine the possible cause of growth-inhibition. Results showed that AHE-EA, ATE-Hex, and ATE-EA were able to inhibit the proliferation of ELT3 and primary leiomyoma cells. Among the tested compounds, Quercetin, nobiletin and eriodictyol, significantly decreased the viability of ELT3 and primary leiomyoma cells. Quercetin induced cell cycle arrest of ELT3 cells at Sub-G1 and G2/M phases. Adlay extracts exhibit growth-inhibitory effects on uterine leiomyoma cells. These effects may result from to the combined actions of different compounds, indicating a possibility of matrix effect from the compounds in adlay extract. Therefore, adlay extracts may be considered a feasible alternative therapeutic agent for leiomyoma.